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 <section id="module-ast">
<h1><a class="reference internal" href="#module-ast" title="ast: Abstract Syntax Tree classes and manipulation."><code class="xref py py-mod docutils literal notranslate">ast</code></a> — Abstract Syntax Trees<a class="headerlink" href="#module-ast" title="Permalink to this headline">¶</a></h1>
Source code: <a class="reference external" href="https://github.com/python/cpython/tree/3.10/Lib/ast.py">Lib/ast.py</a>
<hr class="docutils" />
The <a class="reference internal" href="#module-ast" title="ast: Abstract Syntax Tree classes and manipulation."><code class="xref py py-mod docutils literal notranslate">ast</code></a> module helps Python applications to process trees of the Python
abstract syntax grammar. The abstract syntax itself might change with each
Python release; this module helps to find out programmatically what the current
grammar looks like.
An abstract syntax tree can be generated by passing <a class="reference internal" href="#ast.PyCF_ONLY_AST" title="ast.PyCF_ONLY_AST"><code class="xref py py-data docutils literal notranslate">ast.PyCF_ONLY_AST</code></a> as
a flag to the <a class="reference internal" href="functions.html#compile" title="compile"><code class="xref py py-func docutils literal notranslate">compile()</code></a> built-in function, or using the <a class="reference internal" href="#ast.parse" title="ast.parse"><code class="xref py py-func docutils literal notranslate">parse()</code></a>
helper provided in this module. The result will be a tree of objects whose
classes all inherit from <a class="reference internal" href="#ast.AST" title="ast.AST"><code class="xref py py-class docutils literal notranslate">ast.AST</code></a>. An abstract syntax tree can be
compiled into a Python code object using the built-in <a class="reference internal" href="functions.html#compile" title="compile"><code class="xref py py-func docutils literal notranslate">compile()</code></a> function.
<section id="abstract-grammar">
<h2>Abstract Grammar<a class="headerlink" href="#abstract-grammar" title="Permalink to this headline">¶</a></h2>
The abstract grammar is currently defined as follows:
<div class="highlight-asdl notranslate"><div class="highlight"><pre>-- ASDL&#39;s 4 builtin types are:
-- identifier, int, string, constant

module Python
{
 mod = Module(stmt* body, type_ignore* type_ignores)
 | Interactive(stmt* body)
 | Expression(expr body)
 | FunctionType(expr* argtypes, expr returns)

stmt = FunctionDef(identifier name, arguments args,
 stmt* body, expr* decorator_list, expr? returns,
 string? type_comment)
 | AsyncFunctionDef(identifier name, arguments args,
 stmt* body, expr* decorator_list, expr? returns,
 string? type_comment)

| ClassDef(identifier name,
 expr* bases,
 keyword* keywords,
 stmt* body,
 expr* decorator_list)
 | Return(expr? value)

| Delete(expr* targets)
 | Assign(expr* targets, expr value, string? type_comment)
 | AugAssign(expr target, operator op, expr value)
 -- &#39;simple&#39; indicates that we annotate simple name without parens
 | AnnAssign(expr target, expr annotation, expr? value, int simple)

-- use &#39;orelse&#39; because else is a keyword in target languages
 | For(expr target, expr iter, stmt* body, stmt* orelse, string? type_comment)
 | AsyncFor(expr target, expr iter, stmt* body, stmt* orelse, string? type_comment)
 | While(expr test, stmt* body, stmt* orelse)
 | If(expr test, stmt* body, stmt* orelse)
 | With(withitem* items, stmt* body, string? type_comment)
 | AsyncWith(withitem* items, stmt* body, string? type_comment)

| Match(expr subject, match_case* cases)

| Raise(expr? exc, expr? cause)
 | Try(stmt* body, excepthandler* handlers, stmt* orelse, stmt* finalbody)
 | Assert(expr test, expr? msg)

| Import(alias* names)
 | ImportFrom(identifier? module, alias* names, int? level)

-- col_offset is the byte offset in the utf8 string the parser uses
 attributes (int lineno, int col_offset, int? end_lineno, int? end_col_offset)

-- BoolOp() can use left &amp; right?
 expr = BoolOp(boolop op, expr* values)
 | NamedExpr(expr target, expr value)
 | BinOp(expr left, operator op, expr right)
 | UnaryOp(unaryop op, expr operand)
 | Lambda(arguments args, expr body)
 | IfExp(expr test, expr body, expr orelse)
 | Dict(expr* keys, expr* values)
 | Set(expr* elts)
 | ListComp(expr elt, comprehension* generators)
 | SetComp(expr elt, comprehension* generators)
 | DictComp(expr key, expr value, comprehension* generators)
 | GeneratorExp(expr elt, comprehension* generators)
 -- the grammar constrains where yield expressions can occur
 | Await(expr value)
 | Yield(expr? value)
 | YieldFrom(expr value)
 -- need sequences for compare to distinguish between
 -- x &lt; 4 &lt; 3 and (x &lt; 4) &lt; 3
 | Compare(expr left, cmpop* ops, expr* comparators)
 | Call(expr func, expr* args, keyword* keywords)
 | FormattedValue(expr value, int conversion, expr? format_spec)
 | JoinedStr(expr* values)
 | Constant(constant value, string? kind)

-- the following expression can appear in assignment context
 | Attribute(expr value, identifier attr, expr_context ctx)
 | Subscript(expr value, expr slice, expr_context ctx)
 | Starred(expr value, expr_context ctx)
 | Name(identifier id, expr_context ctx)
 | List(expr* elts, expr_context ctx)
 | Tuple(expr* elts, expr_context ctx)

-- can appear only in Subscript
 | Slice(expr? lower, expr? upper, expr? step)

expr_context = Load | Store | Del

boolop = And | Or

unaryop = Invert | Not | UAdd | USub

cmpop = Eq | NotEq | Lt | LtE | Gt | GtE | Is | IsNot | In | NotIn

comprehension = (expr target, expr iter, expr* ifs, int is_async)

excepthandler = ExceptHandler(expr? type, identifier? name, stmt* body)
 attributes (int lineno, int col_offset, int? end_lineno, int? end_col_offset)

arguments = (arg* posonlyargs, arg* args, arg? vararg, arg* kwonlyargs,
 expr* kw_defaults, arg? kwarg, expr* defaults)

arg = (identifier arg, expr? annotation, string? type_comment)
 attributes (int lineno, int col_offset, int? end_lineno, int? end_col_offset)

-- keyword arguments supplied to call (NULL identifier for **kwargs)
 keyword = (identifier? arg, expr value)
 attributes (int lineno, int col_offset, int? end_lineno, int? end_col_offset)

-- import name with optional &#39;as&#39; alias.
 alias = (identifier name, identifier? asname)
 attributes (int lineno, int col_offset, int? end_lineno, int? end_col_offset)

withitem = (expr context_expr, expr? optional_vars)

match_case = (pattern pattern, expr? guard, stmt* body)

pattern = MatchValue(expr value)
 | MatchSingleton(constant value)
 | MatchSequence(pattern* patterns)
 | MatchMapping(expr* keys, pattern* patterns, identifier? rest)
 | MatchClass(expr cls, pattern* patterns, identifier* kwd_attrs, pattern* kwd_patterns)

| MatchStar(identifier? name)
 -- The optional &quot;rest&quot; MatchMapping parameter handles capturing extra mapping keys

| MatchAs(pattern? pattern, identifier? name)
 | MatchOr(pattern* patterns)

attributes (int lineno, int col_offset, int end_lineno, int end_col_offset)

type_ignore = TypeIgnore(int lineno, string tag)
}
</pre></div>
</div>
</section>
<section id="node-classes">
<h2>Node classes<a class="headerlink" href="#node-classes" title="Permalink to this headline">¶</a></h2>
<dl class="py class">
<dt class="sig sig-object py" id="ast.AST">
class ast.AST<a class="headerlink" href="#ast.AST" title="Permalink to this definition">¶</a></dt>
<dd>This is the base of all AST node classes. The actual node classes are
derived from the <code class="file docutils literal notranslate">Parser/Python.asdl</code> file, which is reproduced
<a class="reference internal" href="#abstract-grammar">above</a>. They are defined in the <code class="xref py py-mod docutils literal notranslate">_ast</code> C
module and re-exported in <a class="reference internal" href="#module-ast" title="ast: Abstract Syntax Tree classes and manipulation."><code class="xref py py-mod docutils literal notranslate">ast</code></a>.
There is one class defined for each left-hand side symbol in the abstract
grammar (for example, <code class="xref py py-class docutils literal notranslate">ast.stmt</code> or <code class="xref py py-class docutils literal notranslate">ast.expr</code>). In addition,
there is one class defined for each constructor on the right-hand side; these
classes inherit from the classes for the left-hand side trees. For example,
<a class="reference internal" href="#ast.BinOp" title="ast.BinOp"><code class="xref py py-class docutils literal notranslate">ast.BinOp</code></a> inherits from <code class="xref py py-class docutils literal notranslate">ast.expr</code>. For production rules
with alternatives (aka “sums”), the left-hand side class is abstract: only
instances of specific constructor nodes are ever created.
<dl class="py attribute">
<dt class="sig sig-object py" id="ast.AST._fields">
_fields<a class="headerlink" href="#ast.AST._fields" title="Permalink to this definition">¶</a></dt>
<dd>Each concrete class has an attribute <a class="reference internal" href="#ast.AST._fields" title="ast.AST._fields"><code class="xref py py-attr docutils literal notranslate">_fields</code></a> which gives the names
of all child nodes.
Each instance of a concrete class has one attribute for each child node,
of the type as defined in the grammar. For example, <a class="reference internal" href="#ast.BinOp" title="ast.BinOp"><code class="xref py py-class docutils literal notranslate">ast.BinOp</code></a>
instances have an attribute <code class="xref py py-attr docutils literal notranslate">left</code> of type <code class="xref py py-class docutils literal notranslate">ast.expr</code>.
If these attributes are marked as optional in the grammar (using a
question mark), the value might be <code class="docutils literal notranslate">None</code>. If the attributes can have
zero-or-more values (marked with an asterisk), the values are represented
as Python lists. All possible attributes must be present and have valid
values when compiling an AST with <a class="reference internal" href="functions.html#compile" title="compile"><code class="xref py py-func docutils literal notranslate">compile()</code></a>.
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="ast.AST.lineno">
lineno<a class="headerlink" href="#ast.AST.lineno" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.AST.col_offset">
col_offset<a class="headerlink" href="#ast.AST.col_offset" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.AST.end_lineno">
end_lineno<a class="headerlink" href="#ast.AST.end_lineno" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.AST.end_col_offset">
end_col_offset<a class="headerlink" href="#ast.AST.end_col_offset" title="Permalink to this definition">¶</a></dt>
<dd>Instances of <code class="xref py py-class docutils literal notranslate">ast.expr</code> and <code class="xref py py-class docutils literal notranslate">ast.stmt</code> subclasses have
<a class="reference internal" href="#ast.AST.lineno" title="ast.AST.lineno"><code class="xref py py-attr docutils literal notranslate">lineno</code></a>, <a class="reference internal" href="#ast.AST.col_offset" title="ast.AST.col_offset"><code class="xref py py-attr docutils literal notranslate">col_offset</code></a>, <a class="reference internal" href="#ast.AST.end_lineno" title="ast.AST.end_lineno"><code class="xref py py-attr docutils literal notranslate">end_lineno</code></a>, and
<a class="reference internal" href="#ast.AST.end_col_offset" title="ast.AST.end_col_offset"><code class="xref py py-attr docutils literal notranslate">end_col_offset</code></a> attributes. The <a class="reference internal" href="#ast.AST.lineno" title="ast.AST.lineno"><code class="xref py py-attr docutils literal notranslate">lineno</code></a> and <a class="reference internal" href="#ast.AST.end_lineno" title="ast.AST.end_lineno"><code class="xref py py-attr docutils literal notranslate">end_lineno</code></a>
are the first and last line numbers of source text span (1-indexed so the
first line is line 1) and the <a class="reference internal" href="#ast.AST.col_offset" title="ast.AST.col_offset"><code class="xref py py-attr docutils literal notranslate">col_offset</code></a> and <a class="reference internal" href="#ast.AST.end_col_offset" title="ast.AST.end_col_offset"><code class="xref py py-attr docutils literal notranslate">end_col_offset</code></a>
are the corresponding UTF-8 byte offsets of the first and last tokens that
generated the node. The UTF-8 offset is recorded because the parser uses
UTF-8 internally.
Note that the end positions are not required by the compiler and are
therefore optional. The end offset is after the last symbol, for example
one can get the source segment of a one-line expression node using
<code class="docutils literal notranslate">source_line[node.col_offset : node.end_col_offset]</code>.
</dd></dl>

The constructor of a class <code class="xref py py-class docutils literal notranslate">ast.T</code> parses its arguments as follows:
<ul class="simple">
<li>If there are positional arguments, there must be as many as there are items
in <code class="xref py py-attr docutils literal notranslate">T._fields</code>; they will be assigned as attributes of these names.</li>
<li>If there are keyword arguments, they will set the attributes of the same
names to the given values.</li>
</ul>
For example, to create and populate an <a class="reference internal" href="#ast.UnaryOp" title="ast.UnaryOp"><code class="xref py py-class docutils literal notranslate">ast.UnaryOp</code></a> node, you could
use
<div class="highlight-python3 notranslate"><div class="highlight"><pre>node = ast.UnaryOp()
node.op = ast.USub()
node.operand = ast.Constant()
node.operand.value = 5
node.operand.lineno = 0
node.operand.col_offset = 0
node.lineno = 0
node.col_offset = 0
</pre></div>
</div>
or the more compact
<div class="highlight-python3 notranslate"><div class="highlight"><pre>node = ast.UnaryOp(ast.USub(), ast.Constant(5, lineno=0, col_offset=0),
 lineno=0, col_offset=0)
</pre></div>
</div>
</dd></dl>

<div class="versionchanged">
Changed in version 3.8: Class <a class="reference internal" href="#ast.Constant" title="ast.Constant"><code class="xref py py-class docutils literal notranslate">ast.Constant</code></a> is now used for all constants.
</div>
<div class="versionchanged">
Changed in version 3.9: Simple indices are represented by their value, extended slices are
represented as tuples.
</div>
<div class="deprecated">
Deprecated since version 3.8: Old classes <code class="xref py py-class docutils literal notranslate">ast.Num</code>, <code class="xref py py-class docutils literal notranslate">ast.Str</code>, <code class="xref py py-class docutils literal notranslate">ast.Bytes</code>,
<code class="xref py py-class docutils literal notranslate">ast.NameConstant</code> and <code class="xref py py-class docutils literal notranslate">ast.Ellipsis</code> are still available,
but they will be removed in future Python releases. In the meantime,
instantiating them will return an instance of a different class.
</div>
<div class="deprecated">
Deprecated since version 3.9: Old classes <code class="xref py py-class docutils literal notranslate">ast.Index</code> and <code class="xref py py-class docutils literal notranslate">ast.ExtSlice</code> are still
available, but they will be removed in future Python releases.
In the meantime, instantiating them will return an instance of
a different class.
</div>
<div class="admonition note">
Note
The descriptions of the specific node classes displayed here
were initially adapted from the fantastic <a class="reference external" href="https://greentreesnakes.readthedocs.io/en/latest/">Green Tree
Snakes</a> project and
all its contributors.
</div>
<section id="literals">
<h3>Literals<a class="headerlink" href="#literals" title="Permalink to this headline">¶</a></h3>
<dl class="py class">
<dt class="sig sig-object py" id="ast.Constant">
class ast.Constant(value)<a class="headerlink" href="#ast.Constant" title="Permalink to this definition">¶</a></dt>
<dd>A constant value. The <code class="docutils literal notranslate">value</code> attribute of the <code class="docutils literal notranslate">Constant</code> literal contains the
Python object it represents. The values represented can be simple types
such as a number, string or <code class="docutils literal notranslate">None</code>, but also immutable container types
(tuples and frozensets) if all of their elements are constant.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;123&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=Constant(value=123))
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.FormattedValue">
class ast.FormattedValue(value, conversion, format_spec)<a class="headerlink" href="#ast.FormattedValue" title="Permalink to this definition">¶</a></dt>
<dd>Node representing a single formatting field in an f-string. If the string
contains a single formatting field and nothing else the node can be
isolated otherwise it appears in <a class="reference internal" href="#ast.JoinedStr" title="ast.JoinedStr"><code class="xref py py-class docutils literal notranslate">JoinedStr</code></a>.
<ul class="simple">
<li><code class="docutils literal notranslate">value</code> is any expression node (such as a literal, a variable, or a
function call).</li>
<li><code class="docutils literal notranslate">conversion</code> is an integer:
<ul>
<li>-1: no formatting</li>
<li>115: <code class="docutils literal notranslate">!s</code> string formatting</li>
<li>114: <code class="docutils literal notranslate">!r</code> repr formatting</li>
<li>97: <code class="docutils literal notranslate">!a</code> ascii formatting</li>
</ul>
</li>
<li><code class="docutils literal notranslate">format_spec</code> is a <a class="reference internal" href="#ast.JoinedStr" title="ast.JoinedStr"><code class="xref py py-class docutils literal notranslate">JoinedStr</code></a> node representing the formatting
of the value, or <code class="docutils literal notranslate">None</code> if no format was specified. Both
<code class="docutils literal notranslate">conversion</code> and <code class="docutils literal notranslate">format_spec</code> can be set at the same time.</li>
</ul>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.JoinedStr">
class ast.JoinedStr(values)<a class="headerlink" href="#ast.JoinedStr" title="Permalink to this definition">¶</a></dt>
<dd>An f-string, comprising a series of <a class="reference internal" href="#ast.FormattedValue" title="ast.FormattedValue"><code class="xref py py-class docutils literal notranslate">FormattedValue</code></a> and <a class="reference internal" href="#ast.Constant" title="ast.Constant"><code class="xref py py-class docutils literal notranslate">Constant</code></a>
nodes.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;f&quot;sin({a}) is {sin(a):.3}&quot;&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=JoinedStr(
 values=[
 Constant(value=&#39;sin(&#39;),
 FormattedValue(
 value=Name(id=&#39;a&#39;, ctx=Load()),
 conversion=-1),
 Constant(value=&#39;) is &#39;),
 FormattedValue(
 value=Call(
 func=Name(id=&#39;sin&#39;, ctx=Load()),
 args=[
 Name(id=&#39;a&#39;, ctx=Load())],
 keywords=[]),
 conversion=-1,
 format_spec=JoinedStr(
 values=[
 Constant(value=&#39;.3&#39;)]))]))
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.List">
class ast.List(elts, ctx)<a class="headerlink" href="#ast.List" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.Tuple">
class ast.Tuple(elts, ctx)<a class="headerlink" href="#ast.Tuple" title="Permalink to this definition">¶</a></dt>
<dd>A list or tuple. <code class="docutils literal notranslate">elts</code> holds a list of nodes representing the elements.
<code class="docutils literal notranslate">ctx</code> is <a class="reference internal" href="#ast.Store" title="ast.Store"><code class="xref py py-class docutils literal notranslate">Store</code></a> if the container is an assignment target (i.e.
<code class="docutils literal notranslate">(x,y)=something</code>), and <a class="reference internal" href="#ast.Load" title="ast.Load"><code class="xref py py-class docutils literal notranslate">Load</code></a> otherwise.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;[1, 2, 3]&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=List(
 elts=[
 Constant(value=1),
 Constant(value=2),
 Constant(value=3)],
 ctx=Load()))
&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;(1, 2, 3)&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=Tuple(
 elts=[
 Constant(value=1),
 Constant(value=2),
 Constant(value=3)],
 ctx=Load()))
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Set">
class ast.Set(elts)<a class="headerlink" href="#ast.Set" title="Permalink to this definition">¶</a></dt>
<dd>A set. <code class="docutils literal notranslate">elts</code> holds a list of nodes representing the set’s elements.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;{1, 2, 3}&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=Set(
 elts=[
 Constant(value=1),
 Constant(value=2),
 Constant(value=3)]))
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Dict">
class ast.Dict(keys, values)<a class="headerlink" href="#ast.Dict" title="Permalink to this definition">¶</a></dt>
<dd>A dictionary. <code class="docutils literal notranslate">keys</code> and <code class="docutils literal notranslate">values</code> hold lists of nodes representing the
keys and the values respectively, in matching order (what would be returned
when calling <code class="code docutils literal notranslate">dictionary.keys()</code> and <code class="code docutils literal notranslate">dictionary.values()</code>).
When doing dictionary unpacking using dictionary literals the expression to be
expanded goes in the <code class="docutils literal notranslate">values</code> list, with a <code class="docutils literal notranslate">None</code> at the corresponding
position in <code class="docutils literal notranslate">keys</code>.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;{&quot;a&quot;:1, **d}&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=Dict(
 keys=[
 Constant(value=&#39;a&#39;),
 None],
 values=[
 Constant(value=1),
 Name(id=&#39;d&#39;, ctx=Load())]))
</pre></div>
</div>
</dd></dl>

</section>
<section id="variables">
<h3>Variables<a class="headerlink" href="#variables" title="Permalink to this headline">¶</a></h3>
<dl class="py class">
<dt class="sig sig-object py" id="ast.Name">
class ast.Name(id, ctx)<a class="headerlink" href="#ast.Name" title="Permalink to this definition">¶</a></dt>
<dd>A variable name. <code class="docutils literal notranslate">id</code> holds the name as a string, and <code class="docutils literal notranslate">ctx</code> is one of
the following types.
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Load">
class ast.Load<a class="headerlink" href="#ast.Load" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.Store">
class ast.Store<a class="headerlink" href="#ast.Store" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.Del">
class ast.Del<a class="headerlink" href="#ast.Del" title="Permalink to this definition">¶</a></dt>
<dd>Variable references can be used to load the value of a variable, to assign
a new value to it, or to delete it. Variable references are given a context
to distinguish these cases.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;a&#39;), indent=4))
Module(
 body=[
 Expr(
 value=Name(id=&#39;a&#39;, ctx=Load()))],
 type_ignores=[])

<dl class="py class">
<dt class="sig sig-object py" id="ast.Starred">
class ast.Starred(value, ctx)<a class="headerlink" href="#ast.Starred" title="Permalink to this definition">¶</a></dt>
<dd>A <code class="docutils literal notranslate">*var</code> variable reference. <code class="docutils literal notranslate">value</code> holds the variable, typically a
<a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a> node. This type must be used when building a <a class="reference internal" href="#ast.Call" title="ast.Call"><code class="xref py py-class docutils literal notranslate">Call</code></a>
node with <code class="docutils literal notranslate">*args</code>.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;a, *b = it&#39;), indent=4))
Module(
 body=[
 Assign(
 targets=[
 Tuple(
 elts=[
 Name(id=&#39;a&#39;, ctx=Store()),
 Starred(
 value=Name(id=&#39;b&#39;, ctx=Store()),
 ctx=Store())],
 ctx=Store())],
 value=Name(id=&#39;it&#39;, ctx=Load()))],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

</section>
<section id="expressions">
<h3>Expressions<a class="headerlink" href="#expressions" title="Permalink to this headline">¶</a></h3>
<dl class="py class">
<dt class="sig sig-object py" id="ast.Expr">
class ast.Expr(value)<a class="headerlink" href="#ast.Expr" title="Permalink to this definition">¶</a></dt>
<dd>When an expression, such as a function call, appears as a statement by itself
with its return value not used or stored, it is wrapped in this container.
<code class="docutils literal notranslate">value</code> holds one of the other nodes in this section, a <a class="reference internal" href="#ast.Constant" title="ast.Constant"><code class="xref py py-class docutils literal notranslate">Constant</code></a>, a
<a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a>, a <a class="reference internal" href="#ast.Lambda" title="ast.Lambda"><code class="xref py py-class docutils literal notranslate">Lambda</code></a>, a <a class="reference internal" href="#ast.Yield" title="ast.Yield"><code class="xref py py-class docutils literal notranslate">Yield</code></a> or <a class="reference internal" href="#ast.YieldFrom" title="ast.YieldFrom"><code class="xref py py-class docutils literal notranslate">YieldFrom</code></a> node.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;-a&#39;), indent=4))
Module(
 body=[
 Expr(
 value=UnaryOp(
 op=USub(),
 operand=Name(id=&#39;a&#39;, ctx=Load())))],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.UnaryOp">
class ast.UnaryOp(op, operand)<a class="headerlink" href="#ast.UnaryOp" title="Permalink to this definition">¶</a></dt>
<dd>A unary operation. <code class="docutils literal notranslate">op</code> is the operator, and <code class="docutils literal notranslate">operand</code> any expression
node.
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.UAdd">
class ast.UAdd<a class="headerlink" href="#ast.UAdd" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.USub">
class ast.USub<a class="headerlink" href="#ast.USub" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.Not">
class ast.Not<a class="headerlink" href="#ast.Not" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.Invert">
class ast.Invert<a class="headerlink" href="#ast.Invert" title="Permalink to this definition">¶</a></dt>
<dd>Unary operator tokens. <a class="reference internal" href="#ast.Not" title="ast.Not"><code class="xref py py-class docutils literal notranslate">Not</code></a> is the <code class="docutils literal notranslate">not</code> keyword, <a class="reference internal" href="#ast.Invert" title="ast.Invert"><code class="xref py py-class docutils literal notranslate">Invert</code></a>
is the <code class="docutils literal notranslate">~</code> operator.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;not x&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=UnaryOp(
 op=Not(),
 operand=Name(id=&#39;x&#39;, ctx=Load())))
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.BinOp">
class ast.BinOp(left, op, right)<a class="headerlink" href="#ast.BinOp" title="Permalink to this definition">¶</a></dt>
<dd>A binary operation (like addition or division). <code class="docutils literal notranslate">op</code> is the operator, and
<code class="docutils literal notranslate">left</code> and <code class="docutils literal notranslate">right</code> are any expression nodes.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;x + y&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=BinOp(
 left=Name(id=&#39;x&#39;, ctx=Load()),
 op=Add(),
 right=Name(id=&#39;y&#39;, ctx=Load())))
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Add">
class ast.Add<a class="headerlink" href="#ast.Add" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.Sub">
class ast.Sub<a class="headerlink" href="#ast.Sub" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.Mult">
class ast.Mult<a class="headerlink" href="#ast.Mult" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.Div">
class ast.Div<a class="headerlink" href="#ast.Div" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.FloorDiv">
class ast.FloorDiv<a class="headerlink" href="#ast.FloorDiv" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.Mod">
class ast.Mod<a class="headerlink" href="#ast.Mod" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.Pow">
class ast.Pow<a class="headerlink" href="#ast.Pow" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.LShift">
class ast.LShift<a class="headerlink" href="#ast.LShift" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.RShift">
class ast.RShift<a class="headerlink" href="#ast.RShift" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.BitOr">
class ast.BitOr<a class="headerlink" href="#ast.BitOr" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.BitXor">
class ast.BitXor<a class="headerlink" href="#ast.BitXor" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.BitAnd">
class ast.BitAnd<a class="headerlink" href="#ast.BitAnd" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.MatMult">
class ast.MatMult<a class="headerlink" href="#ast.MatMult" title="Permalink to this definition">¶</a></dt>
<dd>Binary operator tokens.
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.BoolOp">
class ast.BoolOp(op, values)<a class="headerlink" href="#ast.BoolOp" title="Permalink to this definition">¶</a></dt>
<dd>A boolean operation, ‘or’ or ‘and’. <code class="docutils literal notranslate">op</code> is <a class="reference internal" href="#ast.Or" title="ast.Or"><code class="xref py py-class docutils literal notranslate">Or</code></a> or <a class="reference internal" href="#ast.And" title="ast.And"><code class="xref py py-class docutils literal notranslate">And</code></a>.
<code class="docutils literal notranslate">values</code> are the values involved. Consecutive operations with the same
operator, such as <code class="docutils literal notranslate">a or b or c</code>, are collapsed into one node with several
values.
This doesn’t include <code class="docutils literal notranslate">not</code>, which is a <a class="reference internal" href="#ast.UnaryOp" title="ast.UnaryOp"><code class="xref py py-class docutils literal notranslate">UnaryOp</code></a>.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;x or y&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=BoolOp(
 op=Or(),
 values=[
 Name(id=&#39;x&#39;, ctx=Load()),
 Name(id=&#39;y&#39;, ctx=Load())]))
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.And">
class ast.And<a class="headerlink" href="#ast.And" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.Or">
class ast.Or<a class="headerlink" href="#ast.Or" title="Permalink to this definition">¶</a></dt>
<dd>Boolean operator tokens.
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Compare">
class ast.Compare(left, ops, comparators)<a class="headerlink" href="#ast.Compare" title="Permalink to this definition">¶</a></dt>
<dd>A comparison of two or more values. <code class="docutils literal notranslate">left</code> is the first value in the
comparison, <code class="docutils literal notranslate">ops</code> the list of operators, and <code class="docutils literal notranslate">comparators</code> the list
of values after the first element in the comparison.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;1 &lt;= a &lt; 10&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=Compare(
 left=Constant(value=1),
 ops=[
 LtE(),
 Lt()],
 comparators=[
 Name(id=&#39;a&#39;, ctx=Load()),
 Constant(value=10)]))
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Eq">
class ast.Eq<a class="headerlink" href="#ast.Eq" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.NotEq">
class ast.NotEq<a class="headerlink" href="#ast.NotEq" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.Lt">
class ast.Lt<a class="headerlink" href="#ast.Lt" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.LtE">
class ast.LtE<a class="headerlink" href="#ast.LtE" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.Gt">
class ast.Gt<a class="headerlink" href="#ast.Gt" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.GtE">
class ast.GtE<a class="headerlink" href="#ast.GtE" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.Is">
class ast.Is<a class="headerlink" href="#ast.Is" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.IsNot">
class ast.IsNot<a class="headerlink" href="#ast.IsNot" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.In">
class ast.In<a class="headerlink" href="#ast.In" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.NotIn">
class ast.NotIn<a class="headerlink" href="#ast.NotIn" title="Permalink to this definition">¶</a></dt>
<dd>Comparison operator tokens.
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Call">
class ast.Call(func, args, keywords, starargs, kwargs)<a class="headerlink" href="#ast.Call" title="Permalink to this definition">¶</a></dt>
<dd>A function call. <code class="docutils literal notranslate">func</code> is the function, which will often be a
<a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a> or <a class="reference internal" href="#ast.Attribute" title="ast.Attribute"><code class="xref py py-class docutils literal notranslate">Attribute</code></a> object. Of the arguments:
<ul class="simple">
<li><code class="docutils literal notranslate">args</code> holds a list of the arguments passed by position.</li>
<li><code class="docutils literal notranslate">keywords</code> holds a list of <a class="reference internal" href="keyword.html#module-keyword" title="keyword: Test whether a string is a keyword in Python."><code class="xref py py-class docutils literal notranslate">keyword</code></a> objects representing
arguments passed by keyword.</li>
</ul>
When creating a <code class="docutils literal notranslate">Call</code> node, <code class="docutils literal notranslate">args</code> and <code class="docutils literal notranslate">keywords</code> are required, but
they can be empty lists. <code class="docutils literal notranslate">starargs</code> and <code class="docutils literal notranslate">kwargs</code> are optional.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;func(a, b=c, *d, **e)&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=Call(
 func=Name(id=&#39;func&#39;, ctx=Load()),
 args=[
 Name(id=&#39;a&#39;, ctx=Load()),
 Starred(
 value=Name(id=&#39;d&#39;, ctx=Load()),
 ctx=Load())],
 keywords=[
 keyword(
 arg=&#39;b&#39;,
 value=Name(id=&#39;c&#39;, ctx=Load())),
 keyword(
 value=Name(id=&#39;e&#39;, ctx=Load()))]))
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.keyword">
class ast.keyword(arg, value)<a class="headerlink" href="#ast.keyword" title="Permalink to this definition">¶</a></dt>
<dd>A keyword argument to a function call or class definition. <code class="docutils literal notranslate">arg</code> is a raw
string of the parameter name, <code class="docutils literal notranslate">value</code> is a node to pass in.
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.IfExp">
class ast.IfExp(test, body, orelse)<a class="headerlink" href="#ast.IfExp" title="Permalink to this definition">¶</a></dt>
<dd>An expression such as <code class="docutils literal notranslate">a if b else c</code>. Each field holds a single node, so
in the following example, all three are <a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a> nodes.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;a if b else c&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=IfExp(
 test=Name(id=&#39;b&#39;, ctx=Load()),
 body=Name(id=&#39;a&#39;, ctx=Load()),
 orelse=Name(id=&#39;c&#39;, ctx=Load())))
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Attribute">
class ast.Attribute(value, attr, ctx)<a class="headerlink" href="#ast.Attribute" title="Permalink to this definition">¶</a></dt>
<dd>Attribute access, e.g. <code class="docutils literal notranslate">d.keys</code>. <code class="docutils literal notranslate">value</code> is a node, typically a
<a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a>. <code class="docutils literal notranslate">attr</code> is a bare string giving the name of the attribute,
and <code class="docutils literal notranslate">ctx</code> is <a class="reference internal" href="#ast.Load" title="ast.Load"><code class="xref py py-class docutils literal notranslate">Load</code></a>, <a class="reference internal" href="#ast.Store" title="ast.Store"><code class="xref py py-class docutils literal notranslate">Store</code></a> or <a class="reference internal" href="#ast.Del" title="ast.Del"><code class="xref py py-class docutils literal notranslate">Del</code></a> according to how
the attribute is acted on.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;snake.colour&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=Attribute(
 value=Name(id=&#39;snake&#39;, ctx=Load()),
 attr=&#39;colour&#39;,
 ctx=Load()))
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.NamedExpr">
class ast.NamedExpr(target, value)<a class="headerlink" href="#ast.NamedExpr" title="Permalink to this definition">¶</a></dt>
<dd><blockquote>
<div>A named expression. This AST node is produced by the assignment expressions
operator (also known as the walrus operator). As opposed to the <a class="reference internal" href="#ast.Assign" title="ast.Assign"><code class="xref py py-class docutils literal notranslate">Assign</code></a>
node in which the first argument can be multiple nodes, in this case both
<code class="docutils literal notranslate">target</code> and <code class="docutils literal notranslate">value</code> must be single nodes.
</div></blockquote>
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;(x := 4)&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=NamedExpr(
 target=Name(id=&#39;x&#39;, ctx=Store()),
 value=Constant(value=4)))
</pre></div>
</div>
</dd></dl>

<section id="subscripting">
<h4>Subscripting<a class="headerlink" href="#subscripting" title="Permalink to this headline">¶</a></h4>
<dl class="py class">
<dt class="sig sig-object py" id="ast.Subscript">
class ast.Subscript(value, slice, ctx)<a class="headerlink" href="#ast.Subscript" title="Permalink to this definition">¶</a></dt>
<dd>A subscript, such as <code class="docutils literal notranslate">l[1]</code>. <code class="docutils literal notranslate">value</code> is the subscripted object
(usually sequence or mapping). <code class="docutils literal notranslate">slice</code> is an index, slice or key.
It can be a <a class="reference internal" href="#ast.Tuple" title="ast.Tuple"><code class="xref py py-class docutils literal notranslate">Tuple</code></a> and contain a <a class="reference internal" href="#ast.Slice" title="ast.Slice"><code class="xref py py-class docutils literal notranslate">Slice</code></a>.
<code class="docutils literal notranslate">ctx</code> is <a class="reference internal" href="#ast.Load" title="ast.Load"><code class="xref py py-class docutils literal notranslate">Load</code></a>, <a class="reference internal" href="#ast.Store" title="ast.Store"><code class="xref py py-class docutils literal notranslate">Store</code></a> or <a class="reference internal" href="#ast.Del" title="ast.Del"><code class="xref py py-class docutils literal notranslate">Del</code></a>
according to the action performed with the subscript.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;l[1:2, 3]&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=Subscript(
 value=Name(id=&#39;l&#39;, ctx=Load()),
 slice=Tuple(
 elts=[
 Slice(
 lower=Constant(value=1),
 upper=Constant(value=2)),
 Constant(value=3)],
 ctx=Load()),
 ctx=Load()))
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Slice">
class ast.Slice(lower, upper, step)<a class="headerlink" href="#ast.Slice" title="Permalink to this definition">¶</a></dt>
<dd>Regular slicing (on the form <code class="docutils literal notranslate">lower:upper</code> or <code class="docutils literal notranslate">lower:upper:step</code>).
Can occur only inside the slice field of <a class="reference internal" href="#ast.Subscript" title="ast.Subscript"><code class="xref py py-class docutils literal notranslate">Subscript</code></a>, either
directly or as an element of <a class="reference internal" href="#ast.Tuple" title="ast.Tuple"><code class="xref py py-class docutils literal notranslate">Tuple</code></a>.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;l[1:2]&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=Subscript(
 value=Name(id=&#39;l&#39;, ctx=Load()),
 slice=Slice(
 lower=Constant(value=1),
 upper=Constant(value=2)),
 ctx=Load()))
</pre></div>
</div>
</dd></dl>

</section>
<section id="comprehensions">
<h4>Comprehensions<a class="headerlink" href="#comprehensions" title="Permalink to this headline">¶</a></h4>
<dl class="py class">
<dt class="sig sig-object py" id="ast.ListComp">
class ast.ListComp(elt, generators)<a class="headerlink" href="#ast.ListComp" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.SetComp">
class ast.SetComp(elt, generators)<a class="headerlink" href="#ast.SetComp" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.GeneratorExp">
class ast.GeneratorExp(elt, generators)<a class="headerlink" href="#ast.GeneratorExp" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.DictComp">
class ast.DictComp(key, value, generators)<a class="headerlink" href="#ast.DictComp" title="Permalink to this definition">¶</a></dt>
<dd>List and set comprehensions, generator expressions, and dictionary
comprehensions. <code class="docutils literal notranslate">elt</code> (or <code class="docutils literal notranslate">key</code> and <code class="docutils literal notranslate">value</code>) is a single node
representing the part that will be evaluated for each item.
<code class="docutils literal notranslate">generators</code> is a list of <a class="reference internal" href="#ast.comprehension" title="ast.comprehension"><code class="xref py py-class docutils literal notranslate">comprehension</code></a> nodes.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;[x for x in numbers]&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=ListComp(
 elt=Name(id=&#39;x&#39;, ctx=Load()),
 generators=[
 comprehension(
 target=Name(id=&#39;x&#39;, ctx=Store()),
 iter=Name(id=&#39;numbers&#39;, ctx=Load()),
 ifs=[],
 is_async=0)]))
&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;{x: x**2 for x in numbers}&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=DictComp(
 key=Name(id=&#39;x&#39;, ctx=Load()),
 value=BinOp(
 left=Name(id=&#39;x&#39;, ctx=Load()),
 op=Pow(),
 right=Constant(value=2)),
 generators=[
 comprehension(
 target=Name(id=&#39;x&#39;, ctx=Store()),
 iter=Name(id=&#39;numbers&#39;, ctx=Load()),
 ifs=[],
 is_async=0)]))
&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;{x for x in numbers}&#39;, mode=&#39;eval&#39;), indent=4))
Expression(
 body=SetComp(
 elt=Name(id=&#39;x&#39;, ctx=Load()),
 generators=[
 comprehension(
 target=Name(id=&#39;x&#39;, ctx=Store()),
 iter=Name(id=&#39;numbers&#39;, ctx=Load()),
 ifs=[],
 is_async=0)]))
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.comprehension">
class ast.comprehension(target, iter, ifs, is_async)<a class="headerlink" href="#ast.comprehension" title="Permalink to this definition">¶</a></dt>
<dd>One <code class="docutils literal notranslate">for</code> clause in a comprehension. <code class="docutils literal notranslate">target</code> is the reference to use for
each element - typically a <a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a> or <a class="reference internal" href="#ast.Tuple" title="ast.Tuple"><code class="xref py py-class docutils literal notranslate">Tuple</code></a> node. <code class="docutils literal notranslate">iter</code>
is the object to iterate over. <code class="docutils literal notranslate">ifs</code> is a list of test expressions: each
<code class="docutils literal notranslate">for</code> clause can have multiple <code class="docutils literal notranslate">ifs</code>.
<code class="docutils literal notranslate">is_async</code> indicates a comprehension is asynchronous (using an
<code class="docutils literal notranslate">async for</code> instead of <code class="docutils literal notranslate">for</code>). The value is an integer (0 or 1).
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;[ord(c) for line in file for c in line]&#39;, mode=&#39;eval&#39;),
... indent=4)) # Multiple comprehensions in one.
Expression(
 body=ListComp(
 elt=Call(
 func=Name(id=&#39;ord&#39;, ctx=Load()),
 args=[
 Name(id=&#39;c&#39;, ctx=Load())],
 keywords=[]),
 generators=[
 comprehension(
 target=Name(id=&#39;line&#39;, ctx=Store()),
 iter=Name(id=&#39;file&#39;, ctx=Load()),
 ifs=[],
 is_async=0),
 comprehension(
 target=Name(id=&#39;c&#39;, ctx=Store()),
 iter=Name(id=&#39;line&#39;, ctx=Load()),
 ifs=[],
 is_async=0)]))

&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;(n**2 for n in it if n&gt;5 if n&lt;10)&#39;, mode=&#39;eval&#39;),
... indent=4)) # generator comprehension
Expression(
 body=GeneratorExp(
 elt=BinOp(
 left=Name(id=&#39;n&#39;, ctx=Load()),
 op=Pow(),
 right=Constant(value=2)),
 generators=[
 comprehension(
 target=Name(id=&#39;n&#39;, ctx=Store()),
 iter=Name(id=&#39;it&#39;, ctx=Load()),
 ifs=[
 Compare(
 left=Name(id=&#39;n&#39;, ctx=Load()),
 ops=[
 Gt()],
 comparators=[
 Constant(value=5)]),
 Compare(
 left=Name(id=&#39;n&#39;, ctx=Load()),
 ops=[
 Lt()],
 comparators=[
 Constant(value=10)])],
 is_async=0)]))

</section>
</section>
<section id="statements">
<h3>Statements<a class="headerlink" href="#statements" title="Permalink to this headline">¶</a></h3>
<dl class="py class">
<dt class="sig sig-object py" id="ast.Assign">
class ast.Assign(targets, value, type_comment)<a class="headerlink" href="#ast.Assign" title="Permalink to this definition">¶</a></dt>
<dd>An assignment. <code class="docutils literal notranslate">targets</code> is a list of nodes, and <code class="docutils literal notranslate">value</code> is a single node.
Multiple nodes in <code class="docutils literal notranslate">targets</code> represents assigning the same value to each.
Unpacking is represented by putting a <a class="reference internal" href="#ast.Tuple" title="ast.Tuple"><code class="xref py py-class docutils literal notranslate">Tuple</code></a> or <a class="reference internal" href="#ast.List" title="ast.List"><code class="xref py py-class docutils literal notranslate">List</code></a>
within <code class="docutils literal notranslate">targets</code>.
<dl class="py attribute">
<dt class="sig sig-object py" id="ast.Assign.type_comment">
type_comment<a class="headerlink" href="#ast.Assign.type_comment" title="Permalink to this definition">¶</a></dt>
<dd><code class="docutils literal notranslate">type_comment</code> is an optional string with the type annotation as a comment.
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.AnnAssign">
class ast.AnnAssign(target, annotation, value, simple)<a class="headerlink" href="#ast.AnnAssign" title="Permalink to this definition">¶</a></dt>
<dd>An assignment with a type annotation. <code class="docutils literal notranslate">target</code> is a single node and can
be a <a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a>, a <a class="reference internal" href="#ast.Attribute" title="ast.Attribute"><code class="xref py py-class docutils literal notranslate">Attribute</code></a> or a <a class="reference internal" href="#ast.Subscript" title="ast.Subscript"><code class="xref py py-class docutils literal notranslate">Subscript</code></a>.
<code class="docutils literal notranslate">annotation</code> is the annotation, such as a <a class="reference internal" href="#ast.Constant" title="ast.Constant"><code class="xref py py-class docutils literal notranslate">Constant</code></a> or <a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a>
node. <code class="docutils literal notranslate">value</code> is a single optional node. <code class="docutils literal notranslate">simple</code> is a boolean integer
set to True for a <a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a> node in <code class="docutils literal notranslate">target</code> that do not appear in
between parenthesis and are hence pure names and not expressions.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;c: int&#39;), indent=4))
Module(
 body=[
 AnnAssign(
 target=Name(id=&#39;c&#39;, ctx=Store()),
 annotation=Name(id=&#39;int&#39;, ctx=Load()),
 simple=1)],
 type_ignores=[])

<dl class="py class">
<dt class="sig sig-object py" id="ast.AugAssign">
class ast.AugAssign(target, op, value)<a class="headerlink" href="#ast.AugAssign" title="Permalink to this definition">¶</a></dt>
<dd>Augmented assignment, such as <code class="docutils literal notranslate">a += 1</code>. In the following example,
<code class="docutils literal notranslate">target</code> is a <a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a> node for <code class="docutils literal notranslate">x</code> (with the <a class="reference internal" href="#ast.Store" title="ast.Store"><code class="xref py py-class docutils literal notranslate">Store</code></a>
context), <code class="docutils literal notranslate">op</code> is <a class="reference internal" href="#ast.Add" title="ast.Add"><code class="xref py py-class docutils literal notranslate">Add</code></a>, and <code class="docutils literal notranslate">value</code> is a <a class="reference internal" href="#ast.Constant" title="ast.Constant"><code class="xref py py-class docutils literal notranslate">Constant</code></a> with
value for 1.
The <code class="docutils literal notranslate">target</code> attribute cannot be of class <a class="reference internal" href="#ast.Tuple" title="ast.Tuple"><code class="xref py py-class docutils literal notranslate">Tuple</code></a> or <a class="reference internal" href="#ast.List" title="ast.List"><code class="xref py py-class docutils literal notranslate">List</code></a>,
unlike the targets of <a class="reference internal" href="#ast.Assign" title="ast.Assign"><code class="xref py py-class docutils literal notranslate">Assign</code></a>.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;x += 2&#39;), indent=4))
Module(
 body=[
 AugAssign(
 target=Name(id=&#39;x&#39;, ctx=Store()),
 op=Add(),
 value=Constant(value=2))],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Raise">
class ast.Raise(exc, cause)<a class="headerlink" href="#ast.Raise" title="Permalink to this definition">¶</a></dt>
<dd>A <code class="docutils literal notranslate">raise</code> statement. <code class="docutils literal notranslate">exc</code> is the exception object to be raised, normally a
<a class="reference internal" href="#ast.Call" title="ast.Call"><code class="xref py py-class docutils literal notranslate">Call</code></a> or <a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a>, or <code class="docutils literal notranslate">None</code> for a standalone <code class="docutils literal notranslate">raise</code>.
<code class="docutils literal notranslate">cause</code> is the optional part for <code class="docutils literal notranslate">y</code> in <code class="docutils literal notranslate">raise x from y</code>.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;raise x from y&#39;), indent=4))
Module(
 body=[
 Raise(
 exc=Name(id=&#39;x&#39;, ctx=Load()),
 cause=Name(id=&#39;y&#39;, ctx=Load()))],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Assert">
class ast.Assert(test, msg)<a class="headerlink" href="#ast.Assert" title="Permalink to this definition">¶</a></dt>
<dd>An assertion. <code class="docutils literal notranslate">test</code> holds the condition, such as a <a class="reference internal" href="#ast.Compare" title="ast.Compare"><code class="xref py py-class docutils literal notranslate">Compare</code></a> node.
<code class="docutils literal notranslate">msg</code> holds the failure message.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;assert x,y&#39;), indent=4))
Module(
 body=[
 Assert(
 test=Name(id=&#39;x&#39;, ctx=Load()),
 msg=Name(id=&#39;y&#39;, ctx=Load()))],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Delete">
class ast.Delete(targets)<a class="headerlink" href="#ast.Delete" title="Permalink to this definition">¶</a></dt>
<dd>Represents a <code class="docutils literal notranslate">del</code> statement. <code class="docutils literal notranslate">targets</code> is a list of nodes, such as
<a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a>, <a class="reference internal" href="#ast.Attribute" title="ast.Attribute"><code class="xref py py-class docutils literal notranslate">Attribute</code></a> or <a class="reference internal" href="#ast.Subscript" title="ast.Subscript"><code class="xref py py-class docutils literal notranslate">Subscript</code></a> nodes.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;del x,y,z&#39;), indent=4))
Module(
 body=[
 Delete(
 targets=[
 Name(id=&#39;x&#39;, ctx=Del()),
 Name(id=&#39;y&#39;, ctx=Del()),
 Name(id=&#39;z&#39;, ctx=Del())])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Pass">
class ast.Pass<a class="headerlink" href="#ast.Pass" title="Permalink to this definition">¶</a></dt>
<dd>A <code class="docutils literal notranslate">pass</code> statement.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;pass&#39;), indent=4))
Module(
 body=[
 Pass()],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

Other statements which are only applicable inside functions or loops are
described in other sections.
<section id="imports">
<h4>Imports<a class="headerlink" href="#imports" title="Permalink to this headline">¶</a></h4>
<dl class="py class">
<dt class="sig sig-object py" id="ast.Import">
class ast.Import(names)<a class="headerlink" href="#ast.Import" title="Permalink to this definition">¶</a></dt>
<dd>An import statement. <code class="docutils literal notranslate">names</code> is a list of <a class="reference internal" href="#ast.alias" title="ast.alias"><code class="xref py py-class docutils literal notranslate">alias</code></a> nodes.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;import x,y,z&#39;), indent=4))
Module(
 body=[
 Import(
 names=[
 alias(name=&#39;x&#39;),
 alias(name=&#39;y&#39;),
 alias(name=&#39;z&#39;)])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.ImportFrom">
class ast.ImportFrom(module, names, level)<a class="headerlink" href="#ast.ImportFrom" title="Permalink to this definition">¶</a></dt>
<dd>Represents <code class="docutils literal notranslate">from x import y</code>. <code class="docutils literal notranslate">module</code> is a raw string of the ‘from’ name,
without any leading dots, or <code class="docutils literal notranslate">None</code> for statements such as <code class="docutils literal notranslate">from . import foo</code>.
<code class="docutils literal notranslate">level</code> is an integer holding the level of the relative import (0 means
absolute import).
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;from y import x,y,z&#39;), indent=4))
Module(
 body=[
 ImportFrom(
 module=&#39;y&#39;,
 names=[
 alias(name=&#39;x&#39;),
 alias(name=&#39;y&#39;),
 alias(name=&#39;z&#39;)],
 level=0)],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.alias">
class ast.alias(name, asname)<a class="headerlink" href="#ast.alias" title="Permalink to this definition">¶</a></dt>
<dd>Both parameters are raw strings of the names. <code class="docutils literal notranslate">asname</code> can be <code class="docutils literal notranslate">None</code> if
the regular name is to be used.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;from ..foo.bar import a as b, c&#39;), indent=4))
Module(
 body=[
 ImportFrom(
 module=&#39;foo.bar&#39;,
 names=[
 alias(name=&#39;a&#39;, asname=&#39;b&#39;),
 alias(name=&#39;c&#39;)],
 level=2)],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

</section>
</section>
<section id="control-flow">
<h3>Control flow<a class="headerlink" href="#control-flow" title="Permalink to this headline">¶</a></h3>
<div class="admonition note">
Note
Optional clauses such as <code class="docutils literal notranslate">else</code> are stored as an empty list if they’re
not present.
</div>
<dl class="py class">
<dt class="sig sig-object py" id="ast.If">
class ast.If(test, body, orelse)<a class="headerlink" href="#ast.If" title="Permalink to this definition">¶</a></dt>
<dd>An <code class="docutils literal notranslate">if</code> statement. <code class="docutils literal notranslate">test</code> holds a single node, such as a <a class="reference internal" href="#ast.Compare" title="ast.Compare"><code class="xref py py-class docutils literal notranslate">Compare</code></a>
node. <code class="docutils literal notranslate">body</code> and <code class="docutils literal notranslate">orelse</code> each hold a list of nodes.
<code class="docutils literal notranslate">elif</code> clauses don’t have a special representation in the AST, but rather
appear as extra <a class="reference internal" href="#ast.If" title="ast.If"><code class="xref py py-class docutils literal notranslate">If</code></a> nodes within the <code class="docutils literal notranslate">orelse</code> section of the
previous one.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;
... if x:
... ...
... elif y:
... ...
... else:
... ...
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 If(
 test=Name(id=&#39;x&#39;, ctx=Load()),
 body=[
 Expr(
 value=Constant(value=Ellipsis))],
 orelse=[
 If(
 test=Name(id=&#39;y&#39;, ctx=Load()),
 body=[
 Expr(
 value=Constant(value=Ellipsis))],
 orelse=[
 Expr(
 value=Constant(value=Ellipsis))])])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.For">
class ast.For(target, iter, body, orelse, type_comment)<a class="headerlink" href="#ast.For" title="Permalink to this definition">¶</a></dt>
<dd>A <code class="docutils literal notranslate">for</code> loop. <code class="docutils literal notranslate">target</code> holds the variable(s) the loop assigns to, as a
single <a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a>, <a class="reference internal" href="#ast.Tuple" title="ast.Tuple"><code class="xref py py-class docutils literal notranslate">Tuple</code></a> or <a class="reference internal" href="#ast.List" title="ast.List"><code class="xref py py-class docutils literal notranslate">List</code></a> node. <code class="docutils literal notranslate">iter</code> holds
the item to be looped over, again as a single node. <code class="docutils literal notranslate">body</code> and <code class="docutils literal notranslate">orelse</code>
contain lists of nodes to execute. Those in <code class="docutils literal notranslate">orelse</code> are executed if the
loop finishes normally, rather than via a <code class="docutils literal notranslate">break</code> statement.
<dl class="py attribute">
<dt class="sig sig-object py" id="ast.For.type_comment">
type_comment<a class="headerlink" href="#ast.For.type_comment" title="Permalink to this definition">¶</a></dt>
<dd><code class="docutils literal notranslate">type_comment</code> is an optional string with the type annotation as a comment.
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.While">
class ast.While(test, body, orelse)<a class="headerlink" href="#ast.While" title="Permalink to this definition">¶</a></dt>
<dd>A <code class="docutils literal notranslate">while</code> loop. <code class="docutils literal notranslate">test</code> holds the condition, such as a <a class="reference internal" href="#ast.Compare" title="ast.Compare"><code class="xref py py-class docutils literal notranslate">Compare</code></a>
node.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;
... while x:
... ...
... else:
... ...
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 While(
 test=Name(id=&#39;x&#39;, ctx=Load()),
 body=[
 Expr(
 value=Constant(value=Ellipsis))],
 orelse=[
 Expr(
 value=Constant(value=Ellipsis))])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Break">
class ast.Break<a class="headerlink" href="#ast.Break" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.Continue">
class ast.Continue<a class="headerlink" href="#ast.Continue" title="Permalink to this definition">¶</a></dt>
<dd>The <code class="docutils literal notranslate">break</code> and <code class="docutils literal notranslate">continue</code> statements.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;\
... for a in b:
... if a &gt; 5:
... break
... else:
... continue
...
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 For(
 target=Name(id=&#39;a&#39;, ctx=Store()),
 iter=Name(id=&#39;b&#39;, ctx=Load()),
 body=[
 If(
 test=Compare(
 left=Name(id=&#39;a&#39;, ctx=Load()),
 ops=[
 Gt()],
 comparators=[
 Constant(value=5)]),
 body=[
 Break()],
 orelse=[
 Continue()])],
 orelse=[])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Try">
class ast.Try(body, handlers, orelse, finalbody)<a class="headerlink" href="#ast.Try" title="Permalink to this definition">¶</a></dt>
<dd><code class="docutils literal notranslate">try</code> blocks. All attributes are list of nodes to execute, except for
<code class="docutils literal notranslate">handlers</code>, which is a list of <a class="reference internal" href="#ast.ExceptHandler" title="ast.ExceptHandler"><code class="xref py py-class docutils literal notranslate">ExceptHandler</code></a> nodes.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;
... try:
... ...
... except Exception:
... ...
... except OtherException as e:
... ...
... else:
... ...
... finally:
... ...
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 Try(
 body=[
 Expr(
 value=Constant(value=Ellipsis))],
 handlers=[
 ExceptHandler(
 type=Name(id=&#39;Exception&#39;, ctx=Load()),
 body=[
 Expr(
 value=Constant(value=Ellipsis))]),
 ExceptHandler(
 type=Name(id=&#39;OtherException&#39;, ctx=Load()),
 name=&#39;e&#39;,
 body=[
 Expr(
 value=Constant(value=Ellipsis))])],
 orelse=[
 Expr(
 value=Constant(value=Ellipsis))],
 finalbody=[
 Expr(
 value=Constant(value=Ellipsis))])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.ExceptHandler">
class ast.ExceptHandler(type, name, body)<a class="headerlink" href="#ast.ExceptHandler" title="Permalink to this definition">¶</a></dt>
<dd>A single <code class="docutils literal notranslate">except</code> clause. <code class="docutils literal notranslate">type</code> is the exception type it will match,
typically a <a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a> node (or <code class="docutils literal notranslate">None</code> for a catch-all <code class="docutils literal notranslate">except:</code> clause).
<code class="docutils literal notranslate">name</code> is a raw string for the name to hold the exception, or <code class="docutils literal notranslate">None</code> if
the clause doesn’t have <code class="docutils literal notranslate">as foo</code>. <code class="docutils literal notranslate">body</code> is a list of nodes.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;\
... try:
... a + 1
... except TypeError:
... pass
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 Try(
 body=[
 Expr(
 value=BinOp(
 left=Name(id=&#39;a&#39;, ctx=Load()),
 op=Add(),
 right=Constant(value=1)))],
 handlers=[
 ExceptHandler(
 type=Name(id=&#39;TypeError&#39;, ctx=Load()),
 body=[
 Pass()])],
 orelse=[],
 finalbody=[])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.With">
class ast.With(items, body, type_comment)<a class="headerlink" href="#ast.With" title="Permalink to this definition">¶</a></dt>
<dd>A <code class="docutils literal notranslate">with</code> block. <code class="docutils literal notranslate">items</code> is a list of <a class="reference internal" href="#ast.withitem" title="ast.withitem"><code class="xref py py-class docutils literal notranslate">withitem</code></a> nodes representing
the context managers, and <code class="docutils literal notranslate">body</code> is the indented block inside the context.
<dl class="py attribute">
<dt class="sig sig-object py" id="ast.With.type_comment">
type_comment<a class="headerlink" href="#ast.With.type_comment" title="Permalink to this definition">¶</a></dt>
<dd><code class="docutils literal notranslate">type_comment</code> is an optional string with the type annotation as a comment.
</dd></dl>

</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.withitem">
class ast.withitem(context_expr, optional_vars)<a class="headerlink" href="#ast.withitem" title="Permalink to this definition">¶</a></dt>
<dd>A single context manager in a <code class="docutils literal notranslate">with</code> block. <code class="docutils literal notranslate">context_expr</code> is the context
manager, often a <a class="reference internal" href="#ast.Call" title="ast.Call"><code class="xref py py-class docutils literal notranslate">Call</code></a> node. <code class="docutils literal notranslate">optional_vars</code> is a <a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a>,
<a class="reference internal" href="#ast.Tuple" title="ast.Tuple"><code class="xref py py-class docutils literal notranslate">Tuple</code></a> or <a class="reference internal" href="#ast.List" title="ast.List"><code class="xref py py-class docutils literal notranslate">List</code></a> for the <code class="docutils literal notranslate">as foo</code> part, or <code class="docutils literal notranslate">None</code> if that
isn’t used.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;\
... with a as b, c as d:
... something(b, d)
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 With(
 items=[
 withitem(
 context_expr=Name(id=&#39;a&#39;, ctx=Load()),
 optional_vars=Name(id=&#39;b&#39;, ctx=Store())),
 withitem(
 context_expr=Name(id=&#39;c&#39;, ctx=Load()),
 optional_vars=Name(id=&#39;d&#39;, ctx=Store()))],
 body=[
 Expr(
 value=Call(
 func=Name(id=&#39;something&#39;, ctx=Load()),
 args=[
 Name(id=&#39;b&#39;, ctx=Load()),
 Name(id=&#39;d&#39;, ctx=Load())],
 keywords=[]))])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

</section>
<section id="pattern-matching">
<h3>Pattern matching<a class="headerlink" href="#pattern-matching" title="Permalink to this headline">¶</a></h3>
<dl class="py class">
<dt class="sig sig-object py" id="ast.Match">
class ast.Match(subject, cases)<a class="headerlink" href="#ast.Match" title="Permalink to this definition">¶</a></dt>
<dd>A <code class="docutils literal notranslate">match</code> statement. <code class="docutils literal notranslate">subject</code> holds the subject of the match (the object
that is being matched against the cases) and <code class="docutils literal notranslate">cases</code> contains an iterable of
<a class="reference internal" href="#ast.match_case" title="ast.match_case"><code class="xref py py-class docutils literal notranslate">match_case</code></a> nodes with the different cases.
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.match_case">
class ast.match_case(pattern, guard, body)<a class="headerlink" href="#ast.match_case" title="Permalink to this definition">¶</a></dt>
<dd>A single case pattern in a <code class="docutils literal notranslate">match</code> statement. <code class="docutils literal notranslate">pattern</code> contains the
match pattern that the subject will be matched against. Note that the
<a class="reference internal" href="#ast.AST" title="ast.AST"><code class="xref py py-class docutils literal notranslate">AST</code></a> nodes produced for patterns differ from those produced for
expressions, even when they share the same syntax.
The <code class="docutils literal notranslate">guard</code> attribute contains an expression that will be evaluated if
the pattern matches the subject.
<code class="docutils literal notranslate">body</code> contains a list of nodes to execute if the pattern matches and
the result of evaluating the guard expression is true.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;
... match x:
... case [x] if x&gt;0:
... ...
... case tuple():
... ...
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 Match(
 subject=Name(id=&#39;x&#39;, ctx=Load()),
 cases=[
 match_case(
 pattern=MatchSequence(
 patterns=[
 MatchAs(name=&#39;x&#39;)]),
 guard=Compare(
 left=Name(id=&#39;x&#39;, ctx=Load()),
 ops=[
 Gt()],
 comparators=[
 Constant(value=0)]),
 body=[
 Expr(
 value=Constant(value=Ellipsis))]),
 match_case(
 pattern=MatchClass(
 cls=Name(id=&#39;tuple&#39;, ctx=Load()),
 patterns=[],
 kwd_attrs=[],
 kwd_patterns=[]),
 body=[
 Expr(
 value=Constant(value=Ellipsis))])])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.MatchValue">
class ast.MatchValue(value)<a class="headerlink" href="#ast.MatchValue" title="Permalink to this definition">¶</a></dt>
<dd>A match literal or value pattern that compares by equality. <code class="docutils literal notranslate">value</code> is
an expression node. Permitted value nodes are restricted as described in
the match statement documentation. This pattern succeeds if the match
subject is equal to the evaluated value.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;
... match x:
... case &quot;Relevant&quot;:
... ...
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 Match(
 subject=Name(id=&#39;x&#39;, ctx=Load()),
 cases=[
 match_case(
 pattern=MatchValue(
 value=Constant(value=&#39;Relevant&#39;)),
 body=[
 Expr(
 value=Constant(value=Ellipsis))])])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.MatchSingleton">
class ast.MatchSingleton(value)<a class="headerlink" href="#ast.MatchSingleton" title="Permalink to this definition">¶</a></dt>
<dd>A match literal pattern that compares by identity. <code class="docutils literal notranslate">value</code> is the
singleton to be compared against: <code class="docutils literal notranslate">None</code>, <code class="docutils literal notranslate">True</code>, or <code class="docutils literal notranslate">False</code>. This
pattern succeeds if the match subject is the given constant.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;
... match x:
... case None:
... ...
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 Match(
 subject=Name(id=&#39;x&#39;, ctx=Load()),
 cases=[
 match_case(
 pattern=MatchSingleton(value=None),
 body=[
 Expr(
 value=Constant(value=Ellipsis))])])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.MatchSequence">
class ast.MatchSequence(patterns)<a class="headerlink" href="#ast.MatchSequence" title="Permalink to this definition">¶</a></dt>
<dd>A match sequence pattern. <code class="docutils literal notranslate">patterns</code> contains the patterns to be matched
against the subject elements if the subject is a sequence. Matches a variable
length sequence if one of the subpatterns is a <code class="docutils literal notranslate">MatchStar</code> node, otherwise
matches a fixed length sequence.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;
... match x:
... case [1, 2]:
... ...
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 Match(
 subject=Name(id=&#39;x&#39;, ctx=Load()),
 cases=[
 match_case(
 pattern=MatchSequence(
 patterns=[
 MatchValue(
 value=Constant(value=1)),
 MatchValue(
 value=Constant(value=2))]),
 body=[
 Expr(
 value=Constant(value=Ellipsis))])])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.MatchStar">
class ast.MatchStar(name)<a class="headerlink" href="#ast.MatchStar" title="Permalink to this definition">¶</a></dt>
<dd>Matches the rest of the sequence in a variable length match sequence pattern.
If <code class="docutils literal notranslate">name</code> is not <code class="docutils literal notranslate">None</code>, a list containing the remaining sequence
elements is bound to that name if the overall sequence pattern is successful.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;
... match x:
... case [1, 2, *rest]:
... ...
... case [*_]:
... ...
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 Match(
 subject=Name(id=&#39;x&#39;, ctx=Load()),
 cases=[
 match_case(
 pattern=MatchSequence(
 patterns=[
 MatchValue(
 value=Constant(value=1)),
 MatchValue(
 value=Constant(value=2)),
 MatchStar(name=&#39;rest&#39;)]),
 body=[
 Expr(
 value=Constant(value=Ellipsis))]),
 match_case(
 pattern=MatchSequence(
 patterns=[
 MatchStar()]),
 body=[
 Expr(
 value=Constant(value=Ellipsis))])])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.MatchMapping">
class ast.MatchMapping(keys, patterns, rest)<a class="headerlink" href="#ast.MatchMapping" title="Permalink to this definition">¶</a></dt>
<dd>A match mapping pattern. <code class="docutils literal notranslate">keys</code> is a sequence of expression nodes.
<code class="docutils literal notranslate">patterns</code> is a corresponding sequence of pattern nodes. <code class="docutils literal notranslate">rest</code> is an
optional name that can be specified to capture the remaining mapping elements.
Permitted key expressions are restricted as described in the match statement
documentation.
This pattern succeeds if the subject is a mapping, all evaluated key
expressions are present in the mapping, and the value corresponding to each
key matches the corresponding subpattern. If <code class="docutils literal notranslate">rest</code> is not <code class="docutils literal notranslate">None</code>, a dict
containing the remaining mapping elements is bound to that name if the overall
mapping pattern is successful.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;
... match x:
... case {1: _, 2: _}:
... ...
... case {**rest}:
... ...
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 Match(
 subject=Name(id=&#39;x&#39;, ctx=Load()),
 cases=[
 match_case(
 pattern=MatchMapping(
 keys=[
 Constant(value=1),
 Constant(value=2)],
 patterns=[
 MatchAs(),
 MatchAs()]),
 body=[
 Expr(
 value=Constant(value=Ellipsis))]),
 match_case(
 pattern=MatchMapping(keys=[], patterns=[], rest=&#39;rest&#39;),
 body=[
 Expr(
 value=Constant(value=Ellipsis))])])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.MatchClass">
class ast.MatchClass(cls, patterns, kwd_attrs, kwd_patterns)<a class="headerlink" href="#ast.MatchClass" title="Permalink to this definition">¶</a></dt>
<dd>A match class pattern. <code class="docutils literal notranslate">cls</code> is an expression giving the nominal class to
be matched. <code class="docutils literal notranslate">patterns</code> is a sequence of pattern nodes to be matched against
the class defined sequence of pattern matching attributes. <code class="docutils literal notranslate">kwd_attrs</code> is a
sequence of additional attributes to be matched (specified as keyword arguments
in the class pattern), <code class="docutils literal notranslate">kwd_patterns</code> are the corresponding patterns
(specified as keyword values in the class pattern).
This pattern succeeds if the subject is an instance of the nominated class,
all positional patterns match the corresponding class-defined attributes, and
any specified keyword attributes match their corresponding pattern.
Note: classes may define a property that returns self in order to match a
pattern node against the instance being matched. Several builtin types are
also matched that way, as described in the match statement documentation.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;
... match x:
... case Point2D(0, 0):
... ...
... case Point3D(x=0, y=0, z=0):
... ...
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 Match(
 subject=Name(id=&#39;x&#39;, ctx=Load()),
 cases=[
 match_case(
 pattern=MatchClass(
 cls=Name(id=&#39;Point2D&#39;, ctx=Load()),
 patterns=[
 MatchValue(
 value=Constant(value=0)),
 MatchValue(
 value=Constant(value=0))],
 kwd_attrs=[],
 kwd_patterns=[]),
 body=[
 Expr(
 value=Constant(value=Ellipsis))]),
 match_case(
 pattern=MatchClass(
 cls=Name(id=&#39;Point3D&#39;, ctx=Load()),
 patterns=[],
 kwd_attrs=[
 &#39;x&#39;,
 &#39;y&#39;,
 &#39;z&#39;],
 kwd_patterns=[
 MatchValue(
 value=Constant(value=0)),
 MatchValue(
 value=Constant(value=0)),
 MatchValue(
 value=Constant(value=0))]),
 body=[
 Expr(
 value=Constant(value=Ellipsis))])])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.MatchAs">
class ast.MatchAs(pattern, name)<a class="headerlink" href="#ast.MatchAs" title="Permalink to this definition">¶</a></dt>
<dd>A match “as-pattern”, capture pattern or wildcard pattern. <code class="docutils literal notranslate">pattern</code>
contains the match pattern that the subject will be matched against.
If the pattern is <code class="docutils literal notranslate">None</code>, the node represents a capture pattern (i.e a
bare name) and will always succeed.
The <code class="docutils literal notranslate">name</code> attribute contains the name that will be bound if the pattern
is successful. If <code class="docutils literal notranslate">name</code> is <code class="docutils literal notranslate">None</code>, <code class="docutils literal notranslate">pattern</code> must also be <code class="docutils literal notranslate">None</code>
and the node represents the wildcard pattern.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;
... match x:
... case [x] as y:
... ...
... case _:
... ...
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 Match(
 subject=Name(id=&#39;x&#39;, ctx=Load()),
 cases=[
 match_case(
 pattern=MatchAs(
 pattern=MatchSequence(
 patterns=[
 MatchAs(name=&#39;x&#39;)]),
 name=&#39;y&#39;),
 body=[
 Expr(
 value=Constant(value=Ellipsis))]),
 match_case(
 pattern=MatchAs(),
 body=[
 Expr(
 value=Constant(value=Ellipsis))])])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.MatchOr">
class ast.MatchOr(patterns)<a class="headerlink" href="#ast.MatchOr" title="Permalink to this definition">¶</a></dt>
<dd>A match “or-pattern”. An or-pattern matches each of its subpatterns in turn
to the subject, until one succeeds. The or-pattern is then deemed to
succeed. If none of the subpatterns succeed the or-pattern fails. The
<code class="docutils literal notranslate">patterns</code> attribute contains a list of match pattern nodes that will be
matched against the subject.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;
... match x:
... case [x] | (y):
... ...
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 Match(
 subject=Name(id=&#39;x&#39;, ctx=Load()),
 cases=[
 match_case(
 pattern=MatchOr(
 patterns=[
 MatchSequence(
 patterns=[
 MatchAs(name=&#39;x&#39;)]),
 MatchAs(name=&#39;y&#39;)]),
 body=[
 Expr(
 value=Constant(value=Ellipsis))])])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

</section>
<section id="function-and-class-definitions">
<h3>Function and class definitions<a class="headerlink" href="#function-and-class-definitions" title="Permalink to this headline">¶</a></h3>
<dl class="py class">
<dt class="sig sig-object py" id="ast.FunctionDef">
class ast.FunctionDef(name, args, body, decorator_list, returns, type_comment)<a class="headerlink" href="#ast.FunctionDef" title="Permalink to this definition">¶</a></dt>
<dd>A function definition.
<ul class="simple">
<li><code class="docutils literal notranslate">name</code> is a raw string of the function name.</li>
<li><code class="docutils literal notranslate">args</code> is an <a class="reference internal" href="#ast.arguments" title="ast.arguments"><code class="xref py py-class docutils literal notranslate">arguments</code></a> node.</li>
<li><code class="docutils literal notranslate">body</code> is the list of nodes inside the function.</li>
<li><code class="docutils literal notranslate">decorator_list</code> is the list of decorators to be applied, stored outermost
first (i.e. the first in the list will be applied last).</li>
<li><code class="docutils literal notranslate">returns</code> is the return annotation.</li>
</ul>
<dl class="py attribute">
<dt class="sig sig-object py" id="ast.FunctionDef.type_comment">
type_comment<a class="headerlink" href="#ast.FunctionDef.type_comment" title="Permalink to this definition">¶</a></dt>
<dd><code class="docutils literal notranslate">type_comment</code> is an optional string with the type annotation as a comment.
</dd></dl>

</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Lambda">
class ast.Lambda(args, body)<a class="headerlink" href="#ast.Lambda" title="Permalink to this definition">¶</a></dt>
<dd><code class="docutils literal notranslate">lambda</code> is a minimal function definition that can be used inside an
expression. Unlike <a class="reference internal" href="#ast.FunctionDef" title="ast.FunctionDef"><code class="xref py py-class docutils literal notranslate">FunctionDef</code></a>, <code class="docutils literal notranslate">body</code> holds a single node.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;lambda x,y: ...&#39;), indent=4))
Module(
 body=[
 Expr(
 value=Lambda(
 args=arguments(
 posonlyargs=[],
 args=[
 arg(arg=&#39;x&#39;),
 arg(arg=&#39;y&#39;)],
 kwonlyargs=[],
 kw_defaults=[],
 defaults=[]),
 body=Constant(value=Ellipsis)))],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.arguments">
class ast.arguments(posonlyargs, args, vararg, kwonlyargs, kw_defaults, kwarg, defaults)<a class="headerlink" href="#ast.arguments" title="Permalink to this definition">¶</a></dt>
<dd>The arguments for a function.
<ul class="simple">
<li><code class="docutils literal notranslate">posonlyargs</code>, <code class="docutils literal notranslate">args</code> and <code class="docutils literal notranslate">kwonlyargs</code> are lists of <a class="reference internal" href="#ast.arg" title="ast.arg"><code class="xref py py-class docutils literal notranslate">arg</code></a> nodes.</li>
<li><code class="docutils literal notranslate">vararg</code> and <code class="docutils literal notranslate">kwarg</code> are single <a class="reference internal" href="#ast.arg" title="ast.arg"><code class="xref py py-class docutils literal notranslate">arg</code></a> nodes, referring to the
<code class="docutils literal notranslate">*args, **kwargs</code> parameters.</li>
<li><code class="docutils literal notranslate">kw_defaults</code> is a list of default values for keyword-only arguments. If
one is <code class="docutils literal notranslate">None</code>, the corresponding argument is required.</li>
<li><code class="docutils literal notranslate">defaults</code> is a list of default values for arguments that can be passed
positionally. If there are fewer defaults, they correspond to the last n
arguments.</li>
</ul>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.arg">
class ast.arg(arg, annotation, type_comment)<a class="headerlink" href="#ast.arg" title="Permalink to this definition">¶</a></dt>
<dd>A single argument in a list. <code class="docutils literal notranslate">arg</code> is a raw string of the argument
name, <code class="docutils literal notranslate">annotation</code> is its annotation, such as a <code class="xref py py-class docutils literal notranslate">Str</code> or
<a class="reference internal" href="#ast.Name" title="ast.Name"><code class="xref py py-class docutils literal notranslate">Name</code></a> node.
<dl class="py attribute">
<dt class="sig sig-object py" id="ast.arg.type_comment">
type_comment<a class="headerlink" href="#ast.arg.type_comment" title="Permalink to this definition">¶</a></dt>
<dd><code class="docutils literal notranslate">type_comment</code> is an optional string with the type annotation as a comment
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Return">
class ast.Return(value)<a class="headerlink" href="#ast.Return" title="Permalink to this definition">¶</a></dt>
<dd>A <code class="docutils literal notranslate">return</code> statement.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;return 4&#39;), indent=4))
Module(
 body=[
 Return(
 value=Constant(value=4))],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Yield">
class ast.Yield(value)<a class="headerlink" href="#ast.Yield" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.YieldFrom">
class ast.YieldFrom(value)<a class="headerlink" href="#ast.YieldFrom" title="Permalink to this definition">¶</a></dt>
<dd>A <code class="docutils literal notranslate">yield</code> or <code class="docutils literal notranslate">yield from</code> expression. Because these are expressions, they
must be wrapped in a <a class="reference internal" href="#ast.Expr" title="ast.Expr"><code class="xref py py-class docutils literal notranslate">Expr</code></a> node if the value sent back is not used.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;yield x&#39;), indent=4))
Module(
 body=[
 Expr(
 value=Yield(
 value=Name(id=&#39;x&#39;, ctx=Load())))],
 type_ignores=[])

<dl class="py class">
<dt class="sig sig-object py" id="ast.Global">
class ast.Global(names)<a class="headerlink" href="#ast.Global" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.Nonlocal">
class ast.Nonlocal(names)<a class="headerlink" href="#ast.Nonlocal" title="Permalink to this definition">¶</a></dt>
<dd><code class="docutils literal notranslate">global</code> and <code class="docutils literal notranslate">nonlocal</code> statements. <code class="docutils literal notranslate">names</code> is a list of raw strings.
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&#39;global x,y,z&#39;), indent=4))
Module(
 body=[
 Global(
 names=[
 &#39;x&#39;,
 &#39;y&#39;,
 &#39;z&#39;])],
 type_ignores=[])

<dl class="py class">
<dt class="sig sig-object py" id="ast.ClassDef">
class ast.ClassDef(name, bases, keywords, starargs, kwargs, body, decorator_list)<a class="headerlink" href="#ast.ClassDef" title="Permalink to this definition">¶</a></dt>
<dd>A class definition.
<ul class="simple">
<li><code class="docutils literal notranslate">name</code> is a raw string for the class name</li>
<li><code class="docutils literal notranslate">bases</code> is a list of nodes for explicitly specified base classes.</li>
<li><code class="docutils literal notranslate">keywords</code> is a list of <a class="reference internal" href="keyword.html#module-keyword" title="keyword: Test whether a string is a keyword in Python."><code class="xref py py-class docutils literal notranslate">keyword</code></a> nodes, principally for ‘metaclass’.
Other keywords will be passed to the metaclass, as per <a class="reference external" href="https://www.python.org/dev/peps/pep-3115/">PEP-3115</a>.</li>
<li><code class="docutils literal notranslate">starargs</code> and <code class="docutils literal notranslate">kwargs</code> are each a single node, as in a function call.
starargs will be expanded to join the list of base classes, and kwargs will
be passed to the metaclass.</li>
<li><code class="docutils literal notranslate">body</code> is a list of nodes representing the code within the class
definition.</li>
<li><code class="docutils literal notranslate">decorator_list</code> is a list of nodes, as in <a class="reference internal" href="#ast.FunctionDef" title="ast.FunctionDef"><code class="xref py py-class docutils literal notranslate">FunctionDef</code></a>.</li>
</ul>
<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;\
... @decorator1
... @decorator2
... class Foo(base1, base2, metaclass=meta):
... pass
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 ClassDef(
 name=&#39;Foo&#39;,
 bases=[
 Name(id=&#39;base1&#39;, ctx=Load()),
 Name(id=&#39;base2&#39;, ctx=Load())],
 keywords=[
 keyword(
 arg=&#39;metaclass&#39;,
 value=Name(id=&#39;meta&#39;, ctx=Load()))],
 body=[
 Pass()],
 decorator_list=[
 Name(id=&#39;decorator1&#39;, ctx=Load()),
 Name(id=&#39;decorator2&#39;, ctx=Load())])],
 type_ignores=[])
</pre></div>
</div>
</dd></dl>

</section>
<section id="async-and-await">
<h3>Async and await<a class="headerlink" href="#async-and-await" title="Permalink to this headline">¶</a></h3>
<dl class="py class">
<dt class="sig sig-object py" id="ast.AsyncFunctionDef">
class ast.AsyncFunctionDef(name, args, body, decorator_list, returns, type_comment)<a class="headerlink" href="#ast.AsyncFunctionDef" title="Permalink to this definition">¶</a></dt>
<dd>An <code class="docutils literal notranslate">async def</code> function definition. Has the same fields as
<a class="reference internal" href="#ast.FunctionDef" title="ast.FunctionDef"><code class="xref py py-class docutils literal notranslate">FunctionDef</code></a>.
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.Await">
class ast.Await(value)<a class="headerlink" href="#ast.Await" title="Permalink to this definition">¶</a></dt>
<dd>An <code class="docutils literal notranslate">await</code> expression. <code class="docutils literal notranslate">value</code> is what it waits for.
Only valid in the body of an <a class="reference internal" href="#ast.AsyncFunctionDef" title="ast.AsyncFunctionDef"><code class="xref py py-class docutils literal notranslate">AsyncFunctionDef</code></a>.
</dd></dl>

<div class="highlight-pycon3 notranslate"><div class="highlight"><pre>&gt;&gt;&gt; print(ast.dump(ast.parse(&quot;&quot;&quot;\
... async def f():
... await other_func()
... &quot;&quot;&quot;), indent=4))
Module(
 body=[
 AsyncFunctionDef(
 name=&#39;f&#39;,
 args=arguments(
 posonlyargs=[],
 args=[],
 kwonlyargs=[],
 kw_defaults=[],
 defaults=[]),
 body=[
 Expr(
 value=Await(
 value=Call(
 func=Name(id=&#39;other_func&#39;, ctx=Load()),
 args=[],
 keywords=[])))],
 decorator_list=[])],
 type_ignores=[])
</pre></div>
</div>
<dl class="py class">
<dt class="sig sig-object py" id="ast.AsyncFor">
class ast.AsyncFor(target, iter, body, orelse, type_comment)<a class="headerlink" href="#ast.AsyncFor" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object py" id="ast.AsyncWith">
class ast.AsyncWith(items, body, type_comment)<a class="headerlink" href="#ast.AsyncWith" title="Permalink to this definition">¶</a></dt>
<dd><code class="docutils literal notranslate">async for</code> loops and <code class="docutils literal notranslate">async with</code> context managers. They have the same
fields as <a class="reference internal" href="#ast.For" title="ast.For"><code class="xref py py-class docutils literal notranslate">For</code></a> and <a class="reference internal" href="#ast.With" title="ast.With"><code class="xref py py-class docutils literal notranslate">With</code></a>, respectively. Only valid in the
body of an <a class="reference internal" href="#ast.AsyncFunctionDef" title="ast.AsyncFunctionDef"><code class="xref py py-class docutils literal notranslate">AsyncFunctionDef</code></a>.
</dd></dl>

<div class="admonition note">
Note
When a string is parsed by <a class="reference internal" href="#ast.parse" title="ast.parse"><code class="xref py py-func docutils literal notranslate">ast.parse()</code></a>, operator nodes (subclasses
of <code class="xref py py-class docutils literal notranslate">ast.operator</code>, <code class="xref py py-class docutils literal notranslate">ast.unaryop</code>, <code class="xref py py-class docutils literal notranslate">ast.cmpop</code>,
<code class="xref py py-class docutils literal notranslate">ast.boolop</code> and <code class="xref py py-class docutils literal notranslate">ast.expr_context</code>) on the returned tree
will be singletons. Changes to one will be reflected in all other
occurrences of the same value (e.g. <a class="reference internal" href="#ast.Add" title="ast.Add"><code class="xref py py-class docutils literal notranslate">ast.Add</code></a>).
</div>
</section>
</section>
<section id="ast-helpers">
<h2><a class="reference internal" href="#module-ast" title="ast: Abstract Syntax Tree classes and manipulation."><code class="xref py py-mod docutils literal notranslate">ast</code></a> Helpers<a class="headerlink" href="#ast-helpers" title="Permalink to this headline">¶</a></h2>
Apart from the node classes, the <a class="reference internal" href="#module-ast" title="ast: Abstract Syntax Tree classes and manipulation."><code class="xref py py-mod docutils literal notranslate">ast</code></a> module defines these utility functions
and classes for traversing abstract syntax trees:
<dl class="py function">
<dt class="sig sig-object py" id="ast.parse">
ast.parse(source, filename='&lt;unknown&gt;', mode='exec', *, type_comments=False, feature_version=None)<a class="headerlink" href="#ast.parse" title="Permalink to this definition">¶</a></dt>
<dd>Parse the source into an AST node. Equivalent to <code class="docutils literal notranslate">compile(source,
filename, mode, ast.PyCF_ONLY_AST)</code>.
If <code class="docutils literal notranslate">type_comments=True</code> is given, the parser is modified to check
and return type comments as specified by <a class="pep reference external" href="https://www.python.org/dev/peps/pep-0484">PEP 484</a> and <a class="pep reference external" href="https://www.python.org/dev/peps/pep-0526">PEP 526</a>.
This is equivalent to adding <a class="reference internal" href="#ast.PyCF_TYPE_COMMENTS" title="ast.PyCF_TYPE_COMMENTS"><code class="xref py py-data docutils literal notranslate">ast.PyCF_TYPE_COMMENTS</code></a> to the
flags passed to <a class="reference internal" href="functions.html#compile" title="compile"><code class="xref py py-func docutils literal notranslate">compile()</code></a>. This will report syntax errors
for misplaced type comments. Without this flag, type comments will
be ignored, and the <code class="docutils literal notranslate">type_comment</code> field on selected AST nodes
will always be <code class="docutils literal notranslate">None</code>. In addition, the locations of <code class="docutils literal notranslate"># type:
ignore</code> comments will be returned as the <code class="docutils literal notranslate">type_ignores</code>
attribute of <code class="xref py py-class docutils literal notranslate">Module</code> (otherwise it is always an empty list).
In addition, if <code class="docutils literal notranslate">mode</code> is <code class="docutils literal notranslate">'func_type'</code>, the input syntax is
modified to correspond to <a class="pep reference external" href="https://www.python.org/dev/peps/pep-0484">PEP 484</a> “signature type comments”,
e.g. <code class="docutils literal notranslate">(str, int) -&gt; List[str]</code>.
Also, setting <code class="docutils literal notranslate">feature_version</code> to a tuple <code class="docutils literal notranslate">(major, minor)</code>
will attempt to parse using that Python version’s grammar.
Currently <code class="docutils literal notranslate">major</code> must equal to <code class="docutils literal notranslate">3</code>. For example, setting
<code class="docutils literal notranslate">feature_version=(3, 4)</code> will allow the use of <code class="docutils literal notranslate">async</code> and
<code class="docutils literal notranslate">await</code> as variable names. The lowest supported version is
<code class="docutils literal notranslate">(3, 4)</code>; the highest is <code class="docutils literal notranslate">sys.version_info[0:2]</code>.
If source contains a null character (’0’), <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate">ValueError</code></a> is raised.
<div class="admonition warning">
Warning
Note that successfully parsing source code into an AST object doesn’t
guarantee that the source code provided is valid Python code that can
be executed as the compilation step can raise further <a class="reference internal" href="exceptions.html#SyntaxError" title="SyntaxError"><code class="xref py py-exc docutils literal notranslate">SyntaxError</code></a>
exceptions. For instance, the source <code class="docutils literal notranslate">return 42</code> generates a valid
AST node for a return statement, but it cannot be compiled alone (it needs
to be inside a function node).
In particular, <a class="reference internal" href="#ast.parse" title="ast.parse"><code class="xref py py-func docutils literal notranslate">ast.parse()</code></a> won’t do any scoping checks, which the
compilation step does.
</div>
<div class="admonition warning">
Warning
It is possible to crash the Python interpreter with a
sufficiently large/complex string due to stack depth limitations
in Python’s AST compiler.
</div>
<div class="versionchanged">
Changed in version 3.8: Added <code class="docutils literal notranslate">type_comments</code>, <code class="docutils literal notranslate">mode='func_type'</code> and <code class="docutils literal notranslate">feature_version</code>.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="ast.unparse">
ast.unparse(ast_obj)<a class="headerlink" href="#ast.unparse" title="Permalink to this definition">¶</a></dt>
<dd>Unparse an <a class="reference internal" href="#ast.AST" title="ast.AST"><code class="xref py py-class docutils literal notranslate">ast.AST</code></a> object and generate a string with code
that would produce an equivalent <a class="reference internal" href="#ast.AST" title="ast.AST"><code class="xref py py-class docutils literal notranslate">ast.AST</code></a> object if parsed
back with <a class="reference internal" href="#ast.parse" title="ast.parse"><code class="xref py py-func docutils literal notranslate">ast.parse()</code></a>.
<div class="admonition warning">
Warning
The produced code string will not necessarily be equal to the original
code that generated the <a class="reference internal" href="#ast.AST" title="ast.AST"><code class="xref py py-class docutils literal notranslate">ast.AST</code></a> object (without any compiler
optimizations, such as constant tuples/frozensets).
</div>
<div class="admonition warning">
Warning
Trying to unparse a highly complex expression would result with
<a class="reference internal" href="exceptions.html#RecursionError" title="RecursionError"><code class="xref py py-exc docutils literal notranslate">RecursionError</code></a>.
</div>
<div class="versionadded">
New in version 3.9.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="ast.literal_eval">
ast.literal_eval(node_or_string)<a class="headerlink" href="#ast.literal_eval" title="Permalink to this definition">¶</a></dt>
<dd>Evaluate an expression node or a string containing only a Python literal or
container display. The string or node provided may only consist of the
following Python literal structures: strings, bytes, numbers, tuples, lists,
dicts, sets, booleans, <code class="docutils literal notranslate">None</code> and <code class="docutils literal notranslate">Ellipsis</code>.
This can be used for evaluating strings containing Python values without the
need to parse the values oneself. It is not capable of evaluating
arbitrarily complex expressions, for example involving operators or
indexing.
This function had been documented as “safe” in the past without defining
what that meant. That was misleading. This is specifically designed not to
execute Python code, unlike the more general <a class="reference internal" href="functions.html#eval" title="eval"><code class="xref py py-func docutils literal notranslate">eval()</code></a>. There is no
namespace, no name lookups, or ability to call out. But it is not free from
attack: A relatively small input can lead to memory exhaustion or to C stack
exhaustion, crashing the process. There is also the possibility for
excessive CPU consumption denial of service on some inputs. Calling it on
untrusted data is thus not recommended.
<div class="admonition warning">
Warning
It is possible to crash the Python interpreter due to stack depth
limitations in Python’s AST compiler.
It can raise <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate">ValueError</code></a>, <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate">TypeError</code></a>, <a class="reference internal" href="exceptions.html#SyntaxError" title="SyntaxError"><code class="xref py py-exc docutils literal notranslate">SyntaxError</code></a>,
<a class="reference internal" href="exceptions.html#MemoryError" title="MemoryError"><code class="xref py py-exc docutils literal notranslate">MemoryError</code></a> and <a class="reference internal" href="exceptions.html#RecursionError" title="RecursionError"><code class="xref py py-exc docutils literal notranslate">RecursionError</code></a> depending on the malformed
input.
</div>
<div class="versionchanged">
Changed in version 3.2: Now allows bytes and set literals.
</div>
<div class="versionchanged">
Changed in version 3.9: Now supports creating empty sets with <code class="docutils literal notranslate">'set()'</code>.
</div>
<div class="versionchanged">
Changed in version 3.10: For string inputs, leading spaces and tabs are now stripped.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="ast.get_docstring">
ast.get_docstring(node, clean=True)<a class="headerlink" href="#ast.get_docstring" title="Permalink to this definition">¶</a></dt>
<dd>Return the docstring of the given node (which must be a
<a class="reference internal" href="#ast.FunctionDef" title="ast.FunctionDef"><code class="xref py py-class docutils literal notranslate">FunctionDef</code></a>, <a class="reference internal" href="#ast.AsyncFunctionDef" title="ast.AsyncFunctionDef"><code class="xref py py-class docutils literal notranslate">AsyncFunctionDef</code></a>, <a class="reference internal" href="#ast.ClassDef" title="ast.ClassDef"><code class="xref py py-class docutils literal notranslate">ClassDef</code></a>,
or <code class="xref py py-class docutils literal notranslate">Module</code> node), or <code class="docutils literal notranslate">None</code> if it has no docstring.
If clean is true, clean up the docstring’s indentation with
<a class="reference internal" href="inspect.html#inspect.cleandoc" title="inspect.cleandoc"><code class="xref py py-func docutils literal notranslate">inspect.cleandoc()</code></a>.
<div class="versionchanged">
Changed in version 3.5: <a class="reference internal" href="#ast.AsyncFunctionDef" title="ast.AsyncFunctionDef"><code class="xref py py-class docutils literal notranslate">AsyncFunctionDef</code></a> is now supported.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="ast.get_source_segment">
ast.get_source_segment(source, node, *, padded=False)<a class="headerlink" href="#ast.get_source_segment" title="Permalink to this definition">¶</a></dt>
<dd>Get source code segment of the source that generated node.
If some location information (<code class="xref py py-attr docutils literal notranslate">lineno</code>, <code class="xref py py-attr docutils literal notranslate">end_lineno</code>,
<code class="xref py py-attr docutils literal notranslate">col_offset</code>, or <code class="xref py py-attr docutils literal notranslate">end_col_offset</code>) is missing, return <code class="docutils literal notranslate">None</code>.
If padded is <code class="docutils literal notranslate">True</code>, the first line of a multi-line statement will
be padded with spaces to match its original position.
<div class="versionadded">
New in version 3.8.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="ast.fix_missing_locations">
ast.fix_missing_locations(node)<a class="headerlink" href="#ast.fix_missing_locations" title="Permalink to this definition">¶</a></dt>
<dd>When you compile a node tree with <a class="reference internal" href="functions.html#compile" title="compile"><code class="xref py py-func docutils literal notranslate">compile()</code></a>, the compiler expects
<code class="xref py py-attr docutils literal notranslate">lineno</code> and <code class="xref py py-attr docutils literal notranslate">col_offset</code> attributes for every node that supports
them. This is rather tedious to fill in for generated nodes, so this helper
adds these attributes recursively where not already set, by setting them to
the values of the parent node. It works recursively starting at node.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="ast.increment_lineno">
ast.increment_lineno(node, n=1)<a class="headerlink" href="#ast.increment_lineno" title="Permalink to this definition">¶</a></dt>
<dd>Increment the line number and end line number of each node in the tree
starting at node by n. This is useful to “move code” to a different
location in a file.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="ast.copy_location">
ast.copy_location(new_node, old_node)<a class="headerlink" href="#ast.copy_location" title="Permalink to this definition">¶</a></dt>
<dd>Copy source location (<code class="xref py py-attr docutils literal notranslate">lineno</code>, <code class="xref py py-attr docutils literal notranslate">col_offset</code>, <code class="xref py py-attr docutils literal notranslate">end_lineno</code>,
and <code class="xref py py-attr docutils literal notranslate">end_col_offset</code>) from old_node to new_node if possible,
and return new_node.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="ast.iter_fields">
ast.iter_fields(node)<a class="headerlink" href="#ast.iter_fields" title="Permalink to this definition">¶</a></dt>
<dd>Yield a tuple of <code class="docutils literal notranslate">(fieldname, value)</code> for each field in <code class="docutils literal notranslate">node._fields</code>
that is present on node.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="ast.iter_child_nodes">
ast.iter_child_nodes(node)<a class="headerlink" href="#ast.iter_child_nodes" title="Permalink to this definition">¶</a></dt>
<dd>Yield all direct child nodes of node, that is, all fields that are nodes
and all items of fields that are lists of nodes.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="ast.walk">
ast.walk(node)<a class="headerlink" href="#ast.walk" title="Permalink to this definition">¶</a></dt>
<dd>Recursively yield all descendant nodes in the tree starting at node
(including node itself), in no specified order. This is useful if you only
want to modify nodes in place and don’t care about the context.
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.NodeVisitor">
class ast.NodeVisitor<a class="headerlink" href="#ast.NodeVisitor" title="Permalink to this definition">¶</a></dt>
<dd>A node visitor base class that walks the abstract syntax tree and calls a
visitor function for every node found. This function may return a value
which is forwarded by the <a class="reference internal" href="#ast.NodeVisitor.visit" title="ast.NodeVisitor.visit"><code class="xref py py-meth docutils literal notranslate">visit()</code></a> method.
This class is meant to be subclassed, with the subclass adding visitor
methods.
<dl class="py method">
<dt class="sig sig-object py" id="ast.NodeVisitor.visit">
visit(node)<a class="headerlink" href="#ast.NodeVisitor.visit" title="Permalink to this definition">¶</a></dt>
<dd>Visit a node. The default implementation calls the method called
<code class="samp docutils literal notranslate">self.visit_classname</code> where classname is the name of the node
class, or <a class="reference internal" href="#ast.NodeVisitor.generic_visit" title="ast.NodeVisitor.generic_visit"><code class="xref py py-meth docutils literal notranslate">generic_visit()</code></a> if that method doesn’t exist.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="ast.NodeVisitor.generic_visit">
generic_visit(node)<a class="headerlink" href="#ast.NodeVisitor.generic_visit" title="Permalink to this definition">¶</a></dt>
<dd>This visitor calls <a class="reference internal" href="#ast.NodeVisitor.visit" title="ast.NodeVisitor.visit"><code class="xref py py-meth docutils literal notranslate">visit()</code></a> on all children of the node.
Note that child nodes of nodes that have a custom visitor method won’t be
visited unless the visitor calls <a class="reference internal" href="#ast.NodeVisitor.generic_visit" title="ast.NodeVisitor.generic_visit"><code class="xref py py-meth docutils literal notranslate">generic_visit()</code></a> or visits them
itself.
</dd></dl>

Don’t use the <a class="reference internal" href="#ast.NodeVisitor" title="ast.NodeVisitor"><code class="xref py py-class docutils literal notranslate">NodeVisitor</code></a> if you want to apply changes to nodes
during traversal. For this a special visitor exists
(<a class="reference internal" href="#ast.NodeTransformer" title="ast.NodeTransformer"><code class="xref py py-class docutils literal notranslate">NodeTransformer</code></a>) that allows modifications.
<div class="deprecated">
Deprecated since version 3.8: Methods <code class="xref py py-meth docutils literal notranslate">visit_Num()</code>, <code class="xref py py-meth docutils literal notranslate">visit_Str()</code>, <code class="xref py py-meth docutils literal notranslate">visit_Bytes()</code>,
<code class="xref py py-meth docutils literal notranslate">visit_NameConstant()</code> and <code class="xref py py-meth docutils literal notranslate">visit_Ellipsis()</code> are deprecated
now and will not be called in future Python versions. Add the
<code class="xref py py-meth docutils literal notranslate">visit_Constant()</code> method to handle all constant nodes.
</div>
</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="ast.NodeTransformer">
class ast.NodeTransformer<a class="headerlink" href="#ast.NodeTransformer" title="Permalink to this definition">¶</a></dt>
<dd>A <a class="reference internal" href="#ast.NodeVisitor" title="ast.NodeVisitor"><code class="xref py py-class docutils literal notranslate">NodeVisitor</code></a> subclass that walks the abstract syntax tree and
allows modification of nodes.
The <a class="reference internal" href="#ast.NodeTransformer" title="ast.NodeTransformer"><code class="xref py py-class docutils literal notranslate">NodeTransformer</code></a> will walk the AST and use the return value of
the visitor methods to replace or remove the old node. If the return value
of the visitor method is <code class="docutils literal notranslate">None</code>, the node will be removed from its
location, otherwise it is replaced with the return value. The return value
may be the original node in which case no replacement takes place.
Here is an example transformer that rewrites all occurrences of name lookups
(<code class="docutils literal notranslate">foo</code>) to <code class="docutils literal notranslate">data['foo']</code>:
<div class="highlight-python3 notranslate"><div class="highlight"><pre>class RewriteName(NodeTransformer):

def visit_Name(self, node):
 return Subscript(
 value=Name(id=&#39;data&#39;, ctx=Load()),
 slice=Constant(value=node.id),
 ctx=node.ctx
 )
</pre></div>
</div>
Keep in mind that if the node you’re operating on has child nodes you must
either transform the child nodes yourself or call the <code class="xref py py-meth docutils literal notranslate">generic_visit()</code>
method for the node first.
For nodes that were part of a collection of statements (that applies to all
statement nodes), the visitor may also return a list of nodes rather than
just a single node.
If <a class="reference internal" href="#ast.NodeTransformer" title="ast.NodeTransformer"><code class="xref py py-class docutils literal notranslate">NodeTransformer</code></a> introduces new nodes (that weren’t part of
original tree) without giving them location information (such as
<code class="xref py py-attr docutils literal notranslate">lineno</code>), <a class="reference internal" href="#ast.fix_missing_locations" title="ast.fix_missing_locations"><code class="xref py py-func docutils literal notranslate">fix_missing_locations()</code></a> should be called with
the new sub-tree to recalculate the location information:
<div class="highlight-python3 notranslate"><div class="highlight"><pre>tree = ast.parse(&#39;foo&#39;, mode=&#39;eval&#39;)
new_tree = fix_missing_locations(RewriteName().visit(tree))
</pre></div>
</div>
Usually you use the transformer like this:
<div class="highlight-python3 notranslate"><div class="highlight"><pre>node = YourTransformer().visit(node)
</pre></div>
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="ast.dump">
ast.dump(node, annotate_fields=True, include_attributes=False, *, indent=None)<a class="headerlink" href="#ast.dump" title="Permalink to this definition">¶</a></dt>
<dd>Return a formatted dump of the tree in node. This is mainly useful for
debugging purposes. If annotate_fields is true (by default),
the returned string will show the names and the values for fields.
If annotate_fields is false, the result string will be more compact by
omitting unambiguous field names. Attributes such as line
numbers and column offsets are not dumped by default. If this is wanted,
include_attributes can be set to true.
If indent is a non-negative integer or string, then the tree will be
pretty-printed with that indent level. An indent level
of 0, negative, or <code class="docutils literal notranslate">&quot;&quot;</code> will only insert newlines. <code class="docutils literal notranslate">None</code> (the default)
selects the single line representation. Using a positive integer indent
indents that many spaces per level. If indent is a string (such as <code class="docutils literal notranslate">&quot;\t&quot;</code>),
that string is used to indent each level.
<div class="versionchanged">
Changed in version 3.9: Added the indent option.
</div>
</dd></dl>

</section>
<section id="compiler-flags">
<h2>Compiler Flags<a class="headerlink" href="#compiler-flags" title="Permalink to this headline">¶</a></h2>
The following flags may be passed to <a class="reference internal" href="functions.html#compile" title="compile"><code class="xref py py-func docutils literal notranslate">compile()</code></a> in order to change
effects on the compilation of a program:
<dl class="py data">
<dt class="sig sig-object py" id="ast.PyCF_ALLOW_TOP_LEVEL_AWAIT">
ast.PyCF_ALLOW_TOP_LEVEL_AWAIT<a class="headerlink" href="#ast.PyCF_ALLOW_TOP_LEVEL_AWAIT" title="Permalink to this definition">¶</a></dt>
<dd>Enables support for top-level <code class="docutils literal notranslate">await</code>, <code class="docutils literal notranslate">async for</code>, <code class="docutils literal notranslate">async with</code>
and async comprehensions.
<div class="versionadded">
New in version 3.8.
</div>
</dd></dl>

<dl class="py data">
<dt class="sig sig-object py" id="ast.PyCF_ONLY_AST">
ast.PyCF_ONLY_AST<a class="headerlink" href="#ast.PyCF_ONLY_AST" title="Permalink to this definition">¶</a></dt>
<dd>Generates and returns an abstract syntax tree instead of returning a
compiled code object.
</dd></dl>

<dl class="py data">
<dt class="sig sig-object py" id="ast.PyCF_TYPE_COMMENTS">
ast.PyCF_TYPE_COMMENTS<a class="headerlink" href="#ast.PyCF_TYPE_COMMENTS" title="Permalink to this definition">¶</a></dt>
<dd>Enables support for <a class="pep reference external" href="https://www.python.org/dev/peps/pep-0484">PEP 484</a> and <a class="pep reference external" href="https://www.python.org/dev/peps/pep-0526">PEP 526</a> style type comments
(<code class="docutils literal notranslate"># type: &lt;type&gt;</code>, <code class="docutils literal notranslate"># type: ignore &lt;stuff&gt;</code>).
<div class="versionadded">
New in version 3.8.
</div>
</dd></dl>

</section>
<section id="command-line-usage">
<h2>Command-Line Usage<a class="headerlink" href="#command-line-usage" title="Permalink to this headline">¶</a></h2>
<div class="versionadded">
New in version 3.9.
</div>
The <a class="reference internal" href="#module-ast" title="ast: Abstract Syntax Tree classes and manipulation."><code class="xref py py-mod docutils literal notranslate">ast</code></a> module can be executed as a script from the command line.
It is as simple as:
<div class="highlight-sh notranslate"><div class="highlight"><pre>python -m ast [-m &lt;mode&gt;] [-a] [infile]
</pre></div>
</div>
The following options are accepted:
<dl class="std cmdoption">
<dt class="sig sig-object std" id="cmdoption-ast-h">
-h, --help<a class="headerlink" href="#cmdoption-ast-h" title="Permalink to this definition">¶</a></dt>
<dd>Show the help message and exit.
</dd></dl>

<dl class="std cmdoption">
<dt class="sig sig-object std" id="cmdoption-ast-m">
-m &lt;mode&gt;<a class="headerlink" href="#cmdoption-ast-m" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object std" id="cmdoption-ast-mode">
--mode &lt;mode&gt;<a class="headerlink" href="#cmdoption-ast-mode" title="Permalink to this definition">¶</a></dt>
<dd>Specify what kind of code must be compiled, like the mode argument
in <a class="reference internal" href="#ast.parse" title="ast.parse"><code class="xref py py-func docutils literal notranslate">parse()</code></a>.
</dd></dl>

<dl class="std cmdoption">
<dt class="sig sig-object std" id="cmdoption-ast-no-type-comments">
--no-type-comments<a class="headerlink" href="#cmdoption-ast-no-type-comments" title="Permalink to this definition">¶</a></dt>
<dd>Don’t parse type comments.
</dd></dl>

<dl class="std cmdoption">
<dt class="sig sig-object std" id="cmdoption-ast-a">
-a, --include-attributes<a class="headerlink" href="#cmdoption-ast-a" title="Permalink to this definition">¶</a></dt>
<dd>Include attributes such as line numbers and column offsets.
</dd></dl>

<dl class="std cmdoption">
<dt class="sig sig-object std" id="cmdoption-ast-i">
-i &lt;indent&gt;<a class="headerlink" href="#cmdoption-ast-i" title="Permalink to this definition">¶</a></dt>
<dt class="sig sig-object std" id="cmdoption-ast-indent">
--indent &lt;indent&gt;<a class="headerlink" href="#cmdoption-ast-indent" title="Permalink to this definition">¶</a></dt>
<dd>Indentation of nodes in AST (number of spaces).
</dd></dl>

If <code class="file docutils literal notranslate">infile</code> is specified its contents are parsed to AST and dumped
to stdout. Otherwise, the content is read from stdin.
<div class="admonition seealso">
See also
<a class="reference external" href="https://greentreesnakes.readthedocs.io/">Green Tree Snakes</a>, an external
documentation resource, has good details on working with Python ASTs.
<a class="reference external" href="https://asttokens.readthedocs.io/en/latest/user-guide.html">ASTTokens</a>
annotates Python ASTs with the positions of tokens and text in the source
code that generated them. This is helpful for tools that make source code
transformations.
<a class="reference external" href="https://leoeditor.com/appendices.html#leoast-py">leoAst.py</a> unifies the
token-based and parse-tree-based views of python programs by inserting
two-way links between tokens and ast nodes.
<a class="reference external" href="https://libcst.readthedocs.io/">LibCST</a> parses code as a Concrete Syntax
Tree that looks like an ast tree and keeps all formatting details. It’s
useful for building automated refactoring (codemod) applications and
linters.
<a class="reference external" href="https://parso.readthedocs.io">Parso</a> is a Python parser that supports
error recovery and round-trip parsing for different Python versions (in
multiple Python versions). Parso is also able to list multiple syntax errors
in your python file.
</div>
</section>
</section>

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 <ul>
<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate">ast</code> — Abstract Syntax Trees</a><ul>
<li><a class="reference internal" href="#abstract-grammar">Abstract Grammar</a></li>
<li><a class="reference internal" href="#node-classes">Node classes</a><ul>
<li><a class="reference internal" href="#literals">Literals</a></li>
<li><a class="reference internal" href="#variables">Variables</a></li>
<li><a class="reference internal" href="#expressions">Expressions</a><ul>
<li><a class="reference internal" href="#subscripting">Subscripting</a></li>
<li><a class="reference internal" href="#comprehensions">Comprehensions</a></li>
</ul>
</li>
<li><a class="reference internal" href="#statements">Statements</a><ul>
<li><a class="reference internal" href="#imports">Imports</a></li>
</ul>
</li>
<li><a class="reference internal" href="#control-flow">Control flow</a></li>
<li><a class="reference internal" href="#pattern-matching">Pattern matching</a></li>
<li><a class="reference internal" href="#function-and-class-definitions">Function and class definitions</a></li>
<li><a class="reference internal" href="#async-and-await">Async and await</a></li>
</ul>
</li>
<li><a class="reference internal" href="#ast-helpers"><code class="xref py py-mod docutils literal notranslate">ast</code> Helpers</a></li>
<li><a class="reference internal" href="#compiler-flags">Compiler Flags</a></li>
<li><a class="reference internal" href="#command-line-usage">Command-Line Usage</a></li>
</ul>
</li>
</ul>

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