cpython/ast.py at 3.9 · python/cpython

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parse Function literal_eval Function _raise_malformed_node Function _convert_num Function _convert_signed_num Function _convert Function dump Function _format Function copy_location Function fix_missing_locations Function _fix Function increment_lineno Function iter_fields Function iter_child_nodes Function get_docstring Function _splitlines_no_ff Function _pad_whitespace Function get_source_segment Function walk Function NodeVisitor Class visit Function generic_visit Function visit_Constant Function NodeTransformer Class generic_visit Function _getter Function _setter Function _ABC Class init Function instancecheck Function _new Function Num Class Str Class Bytes Class NameConstant Class Ellipsis Class new Function slice Class Index Class new Function ExtSlice Class new Function _dims_getter Function _dims_setter Function Suite Class AugLoad Class AugStore Class Param Class _Precedence Class next Function _Unparser Class init Function interleave Function items_view Function maybe_newline Function fill Function write Function buffer_writer Function buffer Function block Function delimit Function delimit_if Function require_parens Function get_precedence Function set_precedence Function get_raw_docstring Function get_type_comment Function traverse Function visit Function _write_docstring_and_traverse_body Function visit_Module Function visit_FunctionType Function visit_Expr Function visit_NamedExpr Function visit_Import Function visit_ImportFrom Function visit_Assign Function visit_AugAssign Function visit_AnnAssign Function visit_Return Function visit_Pass Function visit_Break Function visit_Continue Function visit_Delete Function visit_Assert Function visit_Global Function visit_Nonlocal Function visit_Await Function visit_Yield Function visit_YieldFrom Function visit_Raise Function visit_Try Function visit_ExceptHandler Function visit_ClassDef Function visit_FunctionDef Function visit_AsyncFunctionDef Function _function_helper Function visit_For Function visit_AsyncFor Function _for_helper Function visit_If Function visit_While Function visit_With Function visit_AsyncWith Function _str_literal_helper Function escape_char Function _write_str_avoiding_backslashes Function visit_JoinedStr Function visit_FormattedValue Function _fstring_JoinedStr Function _fstring_Constant Function _fstring_FormattedValue Function visit_Name Function _write_docstring Function _write_constant Function visit_Constant Function visit_List Function visit_ListComp Function visit_GeneratorExp Function visit_SetComp Function visit_DictComp Function visit_comprehension Function visit_IfExp Function visit_Set Function visit_Dict Function write_key_value_pair Function write_item Function visit_Tuple Function visit_UnaryOp Function visit_BinOp Function visit_Compare Function visit_BoolOp Function increasing_level_traverse Function visit_Attribute Function visit_Call Function visit_Subscript Function is_simple_tuple Function visit_Starred Function visit_Ellipsis Function visit_Slice Function visit_arg Function visit_arguments Function visit_keyword Function visit_Lambda Function visit_alias Function visit_withitem Function unparse Function main Function

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	"""
	ast
	~~~

	The `ast` 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 and allows modifications of it.

	An abstract syntax tree can be generated by passing `ast.PyCF_ONLY_AST` as
	a flag to the `compile()` builtin function or by using the `parse()`
	function from this module. The result will be a tree of objects whose
	classes all inherit from `ast.AST`.

	A modified abstract syntax tree can be compiled into a Python code object
	using the built-in `compile()` function.

	Additionally various helper functions are provided that make working with
	the trees simpler. The main intention of the helper functions and this
	module in general is to provide an easy to use interface for libraries
	that work tightly with the python syntax (template engines for example).


	:copyright: Copyright 2008 by Armin Ronacher.
	:license: Python License.
	"""
	import sys
	from _ast import *
	from contextlib import contextmanager, nullcontext
	from enum import IntEnum, auto


	def parse(source, filename='<unknown>', mode='exec', *,
	type_comments=False, feature_version=None):
	"""
	Parse the source into an AST node.
	Equivalent to compile(source, filename, mode, PyCF_ONLY_AST).
	Pass type_comments=True to get back type comments where the syntax allows.
	"""
	flags = PyCF_ONLY_AST
	if type_comments:
	flags \|= PyCF_TYPE_COMMENTS
	if isinstance(feature_version, tuple):
	major, minor = feature_version # Should be a 2-tuple.
	assert major == 3
	feature_version = minor
	elif feature_version is None:
	feature_version = -1
	# Else it should be an int giving the minor version for 3.x.
	return compile(source, filename, mode, flags,
	_feature_version=feature_version)


	def literal_eval(node_or_string):
	"""
	Safely evaluate an expression node or a string containing a Python
	expression. The string or node provided may only consist of the following
	Python literal structures: strings, bytes, numbers, tuples, lists, dicts,
	sets, booleans, and None.
	"""
	if isinstance(node_or_string, str):
	node_or_string = parse(node_or_string, mode='eval')
	if isinstance(node_or_string, Expression):
	node_or_string = node_or_string.body
	def _raise_malformed_node(node):
	raise ValueError(f'malformed node or string: {node!r}')
	def _convert_num(node):
	if not isinstance(node, Constant) or type(node.value) not in (int, float, complex):
	_raise_malformed_node(node)
	return node.value
	def _convert_signed_num(node):
	if isinstance(node, UnaryOp) and isinstance(node.op, (UAdd, USub)):
	operand = _convert_num(node.operand)
	if isinstance(node.op, UAdd):
	return + operand
	else:
	return - operand
	return _convert_num(node)
	def _convert(node):
	if isinstance(node, Constant):
	return node.value
	elif isinstance(node, Tuple):
	return tuple(map(_convert, node.elts))
	elif isinstance(node, List):
	return list(map(_convert, node.elts))
	elif isinstance(node, Set):
	return set(map(_convert, node.elts))
	elif (isinstance(node, Call) and isinstance(node.func, Name) and
	node.func.id == 'set' and node.args == node.keywords == []):
	return set()
	elif isinstance(node, Dict):
	if len(node.keys) != len(node.values):
	_raise_malformed_node(node)
	return dict(zip(map(_convert, node.keys),
	map(_convert, node.values)))
	elif isinstance(node, BinOp) and isinstance(node.op, (Add, Sub)):
	left = _convert_signed_num(node.left)
	right = _convert_num(node.right)
	if isinstance(left, (int, float)) and isinstance(right, complex):
	if isinstance(node.op, Add):
	return left + right
	else:
	return left - right
	return _convert_signed_num(node)
	return _convert(node_or_string)


	def dump(node, annotate_fields=True, include_attributes=False, *, indent=None):
	"""
	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. None (the default) selects the single line representation.
	"""
	def _format(node, level=0):
	if indent is not None:
	level += 1
	prefix = '\n' + indent * level
	sep = ',\n' + indent * level
	else:
	prefix = ''
	sep = ', '
	if isinstance(node, AST):
	cls = type(node)
	args = []
	allsimple = True
	keywords = annotate_fields
	for name in node._fields:
	try:
	value = getattr(node, name)
	except AttributeError:
	keywords = True
	continue
	if value is None and getattr(cls, name, ...) is None:
	keywords = True
	continue
	value, simple = _format(value, level)
	allsimple = allsimple and simple
	if keywords:
	args.append('%s=%s' % (name, value))
	else:
	args.append(value)
	if include_attributes and node._attributes:
	for name in node._attributes:
	try:
	value = getattr(node, name)
	except AttributeError:
	continue
	if value is None and getattr(cls, name, ...) is None:
	continue
	value, simple = _format(value, level)
	allsimple = allsimple and simple
	args.append('%s=%s' % (name, value))
	if allsimple and len(args) <= 3:
	return '%s(%s)' % (node.__class__.__name__, ', '.join(args)), not args
	return '%s(%s%s)' % (node.__class__.__name__, prefix, sep.join(args)), False
	elif isinstance(node, list):
	if not node:
	return '[]', True
	return '[%s%s]' % (prefix, sep.join(_format(x, level)[0] for x in node)), False
	return repr(node), True

	if not isinstance(node, AST):
	raise TypeError('expected AST, got %r' % node.__class__.__name__)
	if indent is not None and not isinstance(indent, str):
	indent = ' ' * indent
	return _format(node)[0]


	def copy_location(new_node, old_node):
	"""
	Copy source location (`lineno`, `col_offset`, `end_lineno`, and `end_col_offset`
	attributes) from old_node to new_node if possible, and return new_node.
	"""
	for attr in 'lineno', 'col_offset', 'end_lineno', 'end_col_offset':
	if attr in old_node._attributes and attr in new_node._attributes:
	value = getattr(old_node, attr, None)
	# end_lineno and end_col_offset are optional attributes, and they
	# should be copied whether the value is None or not.
	if value is not None or (
	hasattr(old_node, attr) and attr.startswith("end_")
	):
	setattr(new_node, attr, value)
	return new_node


	def fix_missing_locations(node):
	"""
	When you compile a node tree with compile(), the compiler expects lineno and
	col_offset 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.
	"""
	def _fix(node, lineno, col_offset, end_lineno, end_col_offset):
	if 'lineno' in node._attributes:
	if not hasattr(node, 'lineno'):
	node.lineno = lineno
	else:
	lineno = node.lineno
	if 'end_lineno' in node._attributes:
	if getattr(node, 'end_lineno', None) is None:
	node.end_lineno = end_lineno
	else:
	end_lineno = node.end_lineno
	if 'col_offset' in node._attributes:
	if not hasattr(node, 'col_offset'):
	node.col_offset = col_offset
	else:
	col_offset = node.col_offset
	if 'end_col_offset' in node._attributes:
	if getattr(node, 'end_col_offset', None) is None:
	node.end_col_offset = end_col_offset
	else:
	end_col_offset = node.end_col_offset
	for child in iter_child_nodes(node):
	_fix(child, lineno, col_offset, end_lineno, end_col_offset)
	_fix(node, 1, 0, 1, 0)
	return node


	def increment_lineno(node, n=1):
	"""
	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.
	"""
	for child in walk(node):
	if 'lineno' in child._attributes:
	child.lineno = getattr(child, 'lineno', 0) + n
	if (
	"end_lineno" in child._attributes
	and (end_lineno := getattr(child, "end_lineno", 0)) is not None
	):
	child.end_lineno = end_lineno + n
	return node


	def iter_fields(node):
	"""
	Yield a tuple of ``(fieldname, value)`` for each field in ``node._fields``
	that is present on node.
	"""
	for field in node._fields:
	try:
	yield field, getattr(node, field)
	except AttributeError:
	pass


	def iter_child_nodes(node):
	"""
	Yield all direct child nodes of node, that is, all fields that are nodes
	and all items of fields that are lists of nodes.
	"""
	for name, field in iter_fields(node):
	if isinstance(field, AST):
	yield field
	elif isinstance(field, list):
	for item in field:
	if isinstance(item, AST):
	yield item


	def get_docstring(node, clean=True):
	"""
	Return the docstring for the given node or None if no docstring can
	be found. If the node provided does not have docstrings a TypeError
	will be raised.

	If clean is `True`, all tabs are expanded to spaces and any whitespace
	that can be uniformly removed from the second line onwards is removed.
	"""
	if not isinstance(node, (AsyncFunctionDef, FunctionDef, ClassDef, Module)):
	raise TypeError("%r can't have docstrings" % node.__class__.__name__)
	if not(node.body and isinstance(node.body[0], Expr)):
	return None
	node = node.body[0].value
	if isinstance(node, Str):
	text = node.s
	elif isinstance(node, Constant) and isinstance(node.value, str):
	text = node.value
	else:
	return None
	if clean:
	import inspect
	text = inspect.cleandoc(text)
	return text


	def _splitlines_no_ff(source):
	"""Split a string into lines ignoring form feed and other chars.

	This mimics how the Python parser splits source code.
	"""
	idx = 0
	lines = []
	next_line = ''
	while idx < len(source):
	c = source[idx]
	next_line += c
	idx += 1
	# Keep \r\n together
	if c == '\r' and idx < len(source) and source[idx] == '\n':
	next_line += '\n'
	idx += 1
	if c in '\r\n':
	lines.append(next_line)
	next_line = ''

	if next_line:
	lines.append(next_line)
	return lines


	def _pad_whitespace(source):
	r"""Replace all chars except '\f\t' in a line with spaces."""
	result = ''
	for c in source:
	if c in '\f\t':
	result += c
	else:
	result += ' '
	return result


	def get_source_segment(source, node, *, padded=False):
	"""Get source code segment of the source that generated node.

	If some location information (`lineno`, `end_lineno`, `col_offset`,
	or `end_col_offset`) is missing, return None.

	If padded is `True`, the first line of a multi-line statement will
	be padded with spaces to match its original position.
	"""
	try:
	if node.end_lineno is None or node.end_col_offset is None:
	return None
	lineno = node.lineno - 1
	end_lineno = node.end_lineno - 1
	col_offset = node.col_offset
	end_col_offset = node.end_col_offset
	except AttributeError:
	return None

	lines = _splitlines_no_ff(source)
	if end_lineno == lineno:
	return lines[lineno].encode()[col_offset:end_col_offset].decode()

	if padded:
	padding = _pad_whitespace(lines[lineno].encode()[:col_offset].decode())
	else:
	padding = ''

	first = padding + lines[lineno].encode()[col_offset:].decode()
	last = lines[end_lineno].encode()[:end_col_offset].decode()
	lines = lines[lineno+1:end_lineno]

	lines.insert(0, first)
	lines.append(last)
	return ''.join(lines)


	def walk(node):
	"""
	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.
	"""
	from collections import deque
	todo = deque([node])
	while todo:
	node = todo.popleft()
	todo.extend(iter_child_nodes(node))
	yield node


	class NodeVisitor(object):
	"""
	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 `visit` method.

	This class is meant to be subclassed, with the subclass adding visitor
	methods.

	Per default the visitor functions for the nodes are ``'visit_'`` +
	class name of the node. So a `TryFinally` node visit function would
	be `visit_TryFinally`. This behavior can be changed by overriding
	the `visit` method. If no visitor function exists for a node
	(return value `None`) the `generic_visit` visitor is used instead.

	Don't use the `NodeVisitor` if you want to apply changes to nodes during
	traversing. For this a special visitor exists (`NodeTransformer`) that
	allows modifications.
	"""

	def visit(self, node):
	"""Visit a node."""
	method = 'visit_' + node.__class__.__name__
	visitor = getattr(self, method, self.generic_visit)
	return visitor(node)

	def generic_visit(self, node):
	"""Called if no explicit visitor function exists for a node."""
	for field, value in iter_fields(node):
	if isinstance(value, list):
	for item in value:
	if isinstance(item, AST):
	self.visit(item)
	elif isinstance(value, AST):
	self.visit(value)

	def visit_Constant(self, node):
	value = node.value
	type_name = _const_node_type_names.get(type(value))
	if type_name is None:
	for cls, name in _const_node_type_names.items():
	if isinstance(value, cls):
	type_name = name
	break
	if type_name is not None:
	method = 'visit_' + type_name
	try:
	visitor = getattr(self, method)
	except AttributeError:
	pass
	else:
	import warnings
	warnings.warn(f"{method} is deprecated; add visit_Constant",
	DeprecationWarning, 2)
	return visitor(node)
	return self.generic_visit(node)


	class NodeTransformer(NodeVisitor):
	"""
	A :class:`NodeVisitor` subclass that walks the abstract syntax tree and
	allows modification of nodes.

	The `NodeTransformer` 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 ``None``, 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
	(``foo``) to ``data['foo']``::

	class RewriteName(NodeTransformer):

	def visit_Name(self, node):
	return Subscript(
	value=Name(id='data', ctx=Load()),
	slice=Constant(value=node.id),
	ctx=node.ctx
	)

	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 :meth:`generic_visit`
	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.

	Usually you use the transformer like this::

	node = YourTransformer().visit(node)
	"""

	def generic_visit(self, node):
	for field, old_value in iter_fields(node):
	if isinstance(old_value, list):
	new_values = []
	for value in old_value:
	if isinstance(value, AST):
	value = self.visit(value)
	if value is None:
	continue
	elif not isinstance(value, AST):
	new_values.extend(value)
	continue
	new_values.append(value)
	old_value[:] = new_values
	elif isinstance(old_value, AST):
	new_node = self.visit(old_value)
	if new_node is None:
	delattr(node, field)
	else:
	setattr(node, field, new_node)
	return node


	# If the ast module is loaded more than once, only add deprecated methods once
	if not hasattr(Constant, 'n'):
	# The following code is for backward compatibility.
	# It will be removed in future.

	def _getter(self):
	"""Deprecated. Use value instead."""
	return self.value

	def _setter(self, value):
	self.value = value

	Constant.n = property(_getter, _setter)
	Constant.s = property(_getter, _setter)

	class _ABC(type):

	def __init__(cls, *args):
	cls.__doc__ = """Deprecated AST node class. Use ast.Constant instead"""

	def __instancecheck__(cls, inst):
	if not isinstance(inst, Constant):
	return False
	if cls in _const_types:
	try:
	value = inst.value
	except AttributeError:
	return False
	else:
	return (
	isinstance(value, _const_types[cls]) and
	not isinstance(value, _const_types_not.get(cls, ()))
	)
	return type.__instancecheck__(cls, inst)

	def _new(cls, args, *kwargs):
	for key in kwargs:
	if key not in cls._fields:
	# arbitrary keyword arguments are accepted
	continue
	pos = cls._fields.index(key)
	if pos < len(args):
	raise TypeError(f"{cls.__name__} got multiple values for argument {key!r}")
	if cls in _const_types:
	return Constant(args, *kwargs)
	return Constant.__new__(cls, args, *kwargs)

	class Num(Constant, metaclass=_ABC):
	_fields = ('n',)
	__new__ = _new

	class Str(Constant, metaclass=_ABC):
	_fields = ('s',)
	__new__ = _new

	class Bytes(Constant, metaclass=_ABC):
	_fields = ('s',)
	__new__ = _new

	class NameConstant(Constant, metaclass=_ABC):
	__new__ = _new

	class Ellipsis(Constant, metaclass=_ABC):
	_fields = ()

	def __new__(cls, args, *kwargs):
	if cls is Ellipsis:
	return Constant(..., args, *kwargs)
	return Constant.__new__(cls, args, *kwargs)

	_const_types = {
	Num: (int, float, complex),
	Str: (str,),
	Bytes: (bytes,),
	NameConstant: (type(None), bool),
	Ellipsis: (type(...),),
	}
	_const_types_not = {
	Num: (bool,),
	}

	_const_node_type_names = {
	bool: 'NameConstant', # should be before int
	type(None): 'NameConstant',
	int: 'Num',
	float: 'Num',
	complex: 'Num',
	str: 'Str',
	bytes: 'Bytes',
	type(...): 'Ellipsis',
	}

	class slice(AST):
	"""Deprecated AST node class."""

	class Index(slice):
	"""Deprecated AST node class. Use the index value directly instead."""
	def __new__(cls, value, **kwargs):
	return value

	class ExtSlice(slice):
	"""Deprecated AST node class. Use ast.Tuple instead."""
	def __new__(cls, dims=(), **kwargs):
	return Tuple(list(dims), Load(), **kwargs)

	# If the ast module is loaded more than once, only add deprecated methods once
	if not hasattr(Tuple, 'dims'):
	# The following code is for backward compatibility.
	# It will be removed in future.

	def _dims_getter(self):
	"""Deprecated. Use elts instead."""
	return self.elts

	def _dims_setter(self, value):
	self.elts = value

	Tuple.dims = property(_dims_getter, _dims_setter)

	class Suite(mod):
	"""Deprecated AST node class. Unused in Python 3."""

	class AugLoad(expr_context):
	"""Deprecated AST node class. Unused in Python 3."""

	class AugStore(expr_context):
	"""Deprecated AST node class. Unused in Python 3."""

	class Param(expr_context):
	"""Deprecated AST node class. Unused in Python 3."""


	# Large float and imaginary literals get turned into infinities in the AST.
	# We unparse those infinities to INFSTR.
	_INFSTR = "1e" + repr(sys.float_info.max_10_exp + 1)

	class _Precedence(IntEnum):
	"""Precedence table that originated from python grammar."""

	TUPLE = auto()
	YIELD = auto() # 'yield', 'yield from'
	TEST = auto() # 'if'-'else', 'lambda'
	OR = auto() # 'or'
	AND = auto() # 'and'
	NOT = auto() # 'not'
	CMP = auto() # '<', '>', '==', '>=', '<=', '!=',
	# 'in', 'not in', 'is', 'is not'
	EXPR = auto()
	BOR = EXPR # '\|'
	BXOR = auto() # '^'
	BAND = auto() # '&'
	SHIFT = auto() # '<<', '>>'
	ARITH = auto() # '+', '-'
	TERM = auto() # '*', '@', '/', '%', '//'
	FACTOR = auto() # unary '+', '-', '~'
	POWER = auto() # '**'
	AWAIT = auto() # 'await'
	ATOM = auto()

	def next(self):
	try:
	return self.__class__(self + 1)
	except ValueError:
	return self


	_SINGLE_QUOTES = ("'", '"')
	_MULTI_QUOTES = ('"""', "'''")
	_ALL_QUOTES = (_SINGLE_QUOTES, _MULTI_QUOTES)

	class _Unparser(NodeVisitor):
	"""Methods in this class recursively traverse an AST and
	output source code for the abstract syntax; original formatting
	is disregarded."""

	def __init__(self, *, _avoid_backslashes=False):
	self._source = []
	self._buffer = []
	self._precedences = {}
	self._type_ignores = {}
	self._indent = 0
	self._avoid_backslashes = _avoid_backslashes

	def interleave(self, inter, f, seq):
	"""Call f on each item in seq, calling inter() in between."""
	seq = iter(seq)
	try:
	f(next(seq))
	except StopIteration:
	pass
	else:
	for x in seq:
	inter()
	f(x)

	def items_view(self, traverser, items):
	"""Traverse and separate the given items with a comma and append it to
	the buffer. If items is a single item sequence, a trailing comma
	will be added."""
	if len(items) == 1:
	traverser(items[0])
	self.write(",")
	else:
	self.interleave(lambda: self.write(", "), traverser, items)

	def maybe_newline(self):
	"""Adds a newline if it isn't the start of generated source"""
	if self._source:
	self.write("\n")

	def fill(self, text=""):
	"""Indent a piece of text and append it, according to the current
	indentation level"""
	self.maybe_newline()
	self.write(" " * self._indent + text)

	def write(self, text):
	"""Append a piece of text"""
	self._source.append(text)

	def buffer_writer(self, text):
	self._buffer.append(text)

	@property
	def buffer(self):
	value = "".join(self._buffer)
	self._buffer.clear()
	return value

	@contextmanager
	def block(self, *, extra = None):
	"""A context manager for preparing the source for blocks. It adds
	the character':', increases the indentation on enter and decreases
	the indentation on exit. If extra is given, it will be directly
	appended after the colon character.
	"""
	self.write(":")
	if extra:
	self.write(extra)
	self._indent += 1
	yield
	self._indent -= 1

	@contextmanager
	def delimit(self, start, end):
	"""A context manager for preparing the source for expressions. It adds
	start to the buffer and enters, after exit it adds end."""

	self.write(start)
	yield
	self.write(end)

	def delimit_if(self, start, end, condition):
	if condition:
	return self.delimit(start, end)
	else:
	return nullcontext()

	def require_parens(self, precedence, node):
	"""Shortcut to adding precedence related parens"""
	return self.delimit_if("(", ")", self.get_precedence(node) > precedence)

	def get_precedence(self, node):
	return self._precedences.get(node, _Precedence.TEST)

	def set_precedence(self, precedence, *nodes):
	for node in nodes:
	self._precedences[node] = precedence

	def get_raw_docstring(self, node):
	"""If a docstring node is found in the body of the node parameter,
	return that docstring node, None otherwise.

	Logic mirrored from ``_PyAST_GetDocString``."""
	if not isinstance(
	node, (AsyncFunctionDef, FunctionDef, ClassDef, Module)
	) or len(node.body) < 1:
	return None
	node = node.body[0]
	if not isinstance(node, Expr):
	return None
	node = node.value
	if isinstance(node, Constant) and isinstance(node.value, str):
	return node

	def get_type_comment(self, node):
	comment = self._type_ignores.get(node.lineno) or node.type_comment
	if comment is not None:
	return f" # type: {comment}"

	def traverse(self, node):
	if isinstance(node, list):
	for item in node:
	self.traverse(item)
	else:
	super().visit(node)

	def visit(self, node):
	"""Outputs a source code string that, if converted back to an ast
	(using ast.parse) will generate an AST equivalent to node"""
	self._source = []
	self.traverse(node)
	return "".join(self._source)

	def _write_docstring_and_traverse_body(self, node):
	if (docstring := self.get_raw_docstring(node)):
	self._write_docstring(docstring)
	self.traverse(node.body[1:])
	else:
	self.traverse(node.body)

	def visit_Module(self, node):
	self._type_ignores = {
	ignore.lineno: f"ignore{ignore.tag}"
	for ignore in node.type_ignores
	}
	self._write_docstring_and_traverse_body(node)
	self._type_ignores.clear()

	def visit_FunctionType(self, node):
	with self.delimit("(", ")"):
	self.interleave(
	lambda: self.write(", "), self.traverse, node.argtypes
	)

	self.write(" -> ")
	self.traverse(node.returns)

	def visit_Expr(self, node):
	self.fill()
	self.set_precedence(_Precedence.YIELD, node.value)
	self.traverse(node.value)

	def visit_NamedExpr(self, node):
	with self.require_parens(_Precedence.TUPLE, node):
	self.set_precedence(_Precedence.ATOM, node.target, node.value)
	self.traverse(node.target)
	self.write(" := ")
	self.traverse(node.value)

	def visit_Import(self, node):
	self.fill("import ")
	self.interleave(lambda: self.write(", "), self.traverse, node.names)

	def visit_ImportFrom(self, node):
	self.fill("from ")
	self.write("." * node.level)
	if node.module:
	self.write(node.module)
	self.write(" import ")
	self.interleave(lambda: self.write(", "), self.traverse, node.names)

	def visit_Assign(self, node):
	self.fill()
	for target in node.targets:
	self.traverse(target)
	self.write(" = ")
	self.traverse(node.value)
	if type_comment := self.get_type_comment(node):
	self.write(type_comment)

	def visit_AugAssign(self, node):
	self.fill()
	self.traverse(node.target)
	self.write(" " + self.binop[node.op.__class__.__name__] + "= ")
	self.traverse(node.value)

	def visit_AnnAssign(self, node):
	self.fill()
	with self.delimit_if("(", ")", not node.simple and isinstance(node.target, Name)):
	self.traverse(node.target)
	self.write(": ")
	self.traverse(node.annotation)
	if node.value:
	self.write(" = ")
	self.traverse(node.value)

	def visit_Return(self, node):
	self.fill("return")
	if node.value:
	self.write(" ")
	self.traverse(node.value)

	def visit_Pass(self, node):
	self.fill("pass")

	def visit_Break(self, node):
	self.fill("break")

	def visit_Continue(self, node):
	self.fill("continue")

	def visit_Delete(self, node):
	self.fill("del ")
	self.interleave(lambda: self.write(", "), self.traverse, node.targets)

	def visit_Assert(self, node):
	self.fill("assert ")
	self.traverse(node.test)
	if node.msg:
	self.write(", ")
	self.traverse(node.msg)

	def visit_Global(self, node):
	self.fill("global ")
	self.interleave(lambda: self.write(", "), self.write, node.names)

	def visit_Nonlocal(self, node):
	self.fill("nonlocal ")
	self.interleave(lambda: self.write(", "), self.write, node.names)

	def visit_Await(self, node):
	with self.require_parens(_Precedence.AWAIT, node):
	self.write("await")
	if node.value:
	self.write(" ")
	self.set_precedence(_Precedence.ATOM, node.value)
	self.traverse(node.value)

	def visit_Yield(self, node):
	with self.require_parens(_Precedence.YIELD, node):
	self.write("yield")
	if node.value:
	self.write(" ")
	self.set_precedence(_Precedence.ATOM, node.value)
	self.traverse(node.value)

	def visit_YieldFrom(self, node):
	with self.require_parens(_Precedence.YIELD, node):
	self.write("yield from ")
	if not node.value:
	raise ValueError("Node can't be used without a value attribute.")
	self.set_precedence(_Precedence.ATOM, node.value)
	self.traverse(node.value)

	def visit_Raise(self, node):
	self.fill("raise")
	if not node.exc:
	if node.cause:
	raise ValueError(f"Node can't use cause without an exception.")
	return
	self.write(" ")
	self.traverse(node.exc)
	if node.cause:
	self.write(" from ")
	self.traverse(node.cause)

	def visit_Try(self, node):
	self.fill("try")
	with self.block():
	self.traverse(node.body)
	for ex in node.handlers:
	self.traverse(ex)
	if node.orelse:
	self.fill("else")
	with self.block():
	self.traverse(node.orelse)
	if node.finalbody:
	self.fill("finally")
	with self.block():
	self.traverse(node.finalbody)

	def visit_ExceptHandler(self, node):
	self.fill("except")
	if node.type:
	self.write(" ")
	self.traverse(node.type)
	if node.name:
	self.write(" as ")
	self.write(node.name)
	with self.block():
	self.traverse(node.body)

	def visit_ClassDef(self, node):
	self.maybe_newline()
	for deco in node.decorator_list:
	self.fill("@")
	self.traverse(deco)
	self.fill("class " + node.name)
	with self.delimit_if("(", ")", condition = node.bases or node.keywords):
	comma = False
	for e in node.bases:
	if comma:
	self.write(", ")
	else:
	comma = True
	self.traverse(e)
	for e in node.keywords:
	if comma:
	self.write(", ")
	else:
	comma = True
	self.traverse(e)

	with self.block():
	self._write_docstring_and_traverse_body(node)

	def visit_FunctionDef(self, node):
	self._function_helper(node, "def")

	def visit_AsyncFunctionDef(self, node):
	self._function_helper(node, "async def")

	def _function_helper(self, node, fill_suffix):
	self.maybe_newline()
	for deco in node.decorator_list:
	self.fill("@")
	self.traverse(deco)
	def_str = fill_suffix + " " + node.name
	self.fill(def_str)
	with self.delimit("(", ")"):
	self.traverse(node.args)
	if node.returns:
	self.write(" -> ")
	self.traverse(node.returns)
	with self.block(extra=self.get_type_comment(node)):
	self._write_docstring_and_traverse_body(node)

	def visit_For(self, node):
	self._for_helper("for ", node)

	def visit_AsyncFor(self, node):
	self._for_helper("async for ", node)

	def _for_helper(self, fill, node):
	self.fill(fill)
	self.traverse(node.target)
	self.write(" in ")
	self.traverse(node.iter)
	with self.block(extra=self.get_type_comment(node)):
	self.traverse(node.body)
	if node.orelse:
	self.fill("else")
	with self.block():
	self.traverse(node.orelse)

	def visit_If(self, node):
	self.fill("if ")
	self.traverse(node.test)
	with self.block():
	self.traverse(node.body)
	# collapse nested ifs into equivalent elifs.
	while node.orelse and len(node.orelse) == 1 and isinstance(node.orelse[0], If):
	node = node.orelse[0]
	self.fill("elif ")
	self.traverse(node.test)
	with self.block():
	self.traverse(node.body)
	# final else
	if node.orelse:
	self.fill("else")
	with self.block():
	self.traverse(node.orelse)

	def visit_While(self, node):
	self.fill("while ")
	self.traverse(node.test)
	with self.block():
	self.traverse(node.body)
	if node.orelse:
	self.fill("else")
	with self.block():
	self.traverse(node.orelse)

	def visit_With(self, node):
	self.fill("with ")
	self.interleave(lambda: self.write(", "), self.traverse, node.items)
	with self.block(extra=self.get_type_comment(node)):
	self.traverse(node.body)

	def visit_AsyncWith(self, node):
	self.fill("async with ")
	self.interleave(lambda: self.write(", "), self.traverse, node.items)
	with self.block(extra=self.get_type_comment(node)):
	self.traverse(node.body)

	def _str_literal_helper(
	self, string, *, quote_types=_ALL_QUOTES, escape_special_whitespace=False
	):
	"""Helper for writing string literals, minimizing escapes.
	Returns the tuple (string literal to write, possible quote types).
	"""
	def escape_char(c):
	# \n and \t are non-printable, but we only escape them if
	# escape_special_whitespace is True
	if not escape_special_whitespace and c in "\n\t":
	return c
	# Always escape backslashes and other non-printable characters
	if c == "\\" or not c.isprintable():
	return c.encode("unicode_escape").decode("ascii")
	return c

	escaped_string = "".join(map(escape_char, string))
	possible_quotes = quote_types
	if "\n" in escaped_string:
	possible_quotes = [q for q in possible_quotes if q in _MULTI_QUOTES]
	possible_quotes = [q for q in possible_quotes if q not in escaped_string]
	if not possible_quotes:
	# If there aren't any possible_quotes, fallback to using repr
	# on the original string. Try to use a quote from quote_types,
	# e.g., so that we use triple quotes for docstrings.
	string = repr(string)
	quote = next((q for q in quote_types if string[0] in q), string[0])
	return string[1:-1], [quote]
	if escaped_string:
	# Sort so that we prefer '''"''' over """\""""
	possible_quotes.sort(key=lambda q: q[0] == escaped_string[-1])
	# If we're using triple quotes and we'd need to escape a final
	# quote, escape it
	if possible_quotes[0][0] == escaped_string[-1]:
	assert len(possible_quotes[0]) == 3
	escaped_string = escaped_string[:-1] + "\\" + escaped_string[-1]
	return escaped_string, possible_quotes

	def _write_str_avoiding_backslashes(self, string, *, quote_types=_ALL_QUOTES):
	"""Write string literal value with a best effort attempt to avoid backslashes."""
	string, quote_types = self._str_literal_helper(string, quote_types=quote_types)
	quote_type = quote_types[0]
	self.write(f"{quote_type}{string}{quote_type}")

	def visit_JoinedStr(self, node):
	self.write("f")
	if self._avoid_backslashes:
	self._fstring_JoinedStr(node, self.buffer_writer)
	self._write_str_avoiding_backslashes(self.buffer)
	return

	# If we don't need to avoid backslashes globally (i.e., we only need
	# to avoid them inside FormattedValues), it's cosmetically preferred
	# to use escaped whitespace. That is, it's preferred to use backslashes
	# for cases like: f"{x}\n". To accomplish this, we keep track of what
	# in our buffer corresponds to FormattedValues and what corresponds to
	# Constant parts of the f-string, and allow escapes accordingly.
	buffer = []
	for value in node.values:
	meth = getattr(self, "_fstring_" + type(value).__name__)
	meth(value, self.buffer_writer)
	buffer.append((self.buffer, isinstance(value, Constant)))
	new_buffer = []
	quote_types = _ALL_QUOTES
	for value, is_constant in buffer:
	# Repeatedly narrow down the list of possible quote_types
	value, quote_types = self._str_literal_helper(
	value, quote_types=quote_types,
	escape_special_whitespace=is_constant
	)
	new_buffer.append(value)
	value = "".join(new_buffer)
	quote_type = quote_types[0]
	self.write(f"{quote_type}{value}{quote_type}")

	def visit_FormattedValue(self, node):
	self.write("f")
	self._fstring_FormattedValue(node, self.buffer_writer)
	self._write_str_avoiding_backslashes(self.buffer)

	def _fstring_JoinedStr(self, node, write):
	for value in node.values:
	meth = getattr(self, "_fstring_" + type(value).__name__)
	meth(value, write)

	def _fstring_Constant(self, node, write):
	if not isinstance(node.value, str):
	raise ValueError("Constants inside JoinedStr should be a string.")
	value = node.value.replace("{", "{{").replace("}", "}}")
	write(value)

	def _fstring_FormattedValue(self, node, write):
	write("{")
	unparser = type(self)(_avoid_backslashes=True)
	unparser.set_precedence(_Precedence.TEST.next(), node.value)
	expr = unparser.visit(node.value)
	if expr.startswith("{"):
	write(" ") # Separate pair of opening brackets as "{ {"
	if "\\" in expr:
	raise ValueError("Unable to avoid backslash in f-string expression part")
	write(expr)
	if node.conversion != -1:
	conversion = chr(node.conversion)
	if conversion not in "sra":
	raise ValueError("Unknown f-string conversion.")
	write(f"!{conversion}")
	if node.format_spec:
	write(":")
	meth = getattr(self, "_fstring_" + type(node.format_spec).__name__)
	meth(node.format_spec, write)
	write("}")

	def visit_Name(self, node):
	self.write(node.id)

	def _write_docstring(self, node):
	self.fill()
	if node.kind == "u":
	self.write("u")
	self._write_str_avoiding_backslashes(node.value, quote_types=_MULTI_QUOTES)

	def _write_constant(self, value):
	if isinstance(value, (float, complex)):
	# Substitute overflowing decimal literal for AST infinities,
	# and inf - inf for NaNs.
	self.write(
	repr(value)
	.replace("inf", _INFSTR)
	.replace("nan", f"({_INFSTR}-{_INFSTR})")
	)
	elif self._avoid_backslashes and isinstance(value, str):
	self._write_str_avoiding_backslashes(value)
	else:
	self.write(repr(value))

	def visit_Constant(self, node):
	value = node.value
	if isinstance(value, tuple):
	with self.delimit("(", ")"):
	self.items_view(self._write_constant, value)
	elif value is ...:
	self.write("...")
	else:
	if node.kind == "u":
	self.write("u")
	self._write_constant(node.value)

	def visit_List(self, node):
	with self.delimit("[", "]"):
	self.interleave(lambda: self.write(", "), self.traverse, node.elts)

	def visit_ListComp(self, node):
	with self.delimit("[", "]"):
	self.traverse(node.elt)
	for gen in node.generators:
	self.traverse(gen)

	def visit_GeneratorExp(self, node):
	with self.delimit("(", ")"):
	self.traverse(node.elt)
	for gen in node.generators:
	self.traverse(gen)

	def visit_SetComp(self, node):
	with self.delimit("{", "}"):
	self.traverse(node.elt)
	for gen in node.generators:
	self.traverse(gen)

	def visit_DictComp(self, node):
	with self.delimit("{", "}"):
	self.traverse(node.key)
	self.write(": ")
	self.traverse(node.value)
	for gen in node.generators:
	self.traverse(gen)

	def visit_comprehension(self, node):
	if node.is_async:
	self.write(" async for ")
	else:
	self.write(" for ")
	self.set_precedence(_Precedence.TUPLE, node.target)
	self.traverse(node.target)
	self.write(" in ")
	self.set_precedence(_Precedence.TEST.next(), node.iter, *node.ifs)
	self.traverse(node.iter)
	for if_clause in node.ifs:
	self.write(" if ")
	self.traverse(if_clause)

	def visit_IfExp(self, node):
	with self.require_parens(_Precedence.TEST, node):
	self.set_precedence(_Precedence.TEST.next(), node.body, node.test)
	self.traverse(node.body)
	self.write(" if ")
	self.traverse(node.test)
	self.write(" else ")
	self.set_precedence(_Precedence.TEST, node.orelse)
	self.traverse(node.orelse)

	def visit_Set(self, node):
	if node.elts:
	with self.delimit("{", "}"):
	self.interleave(lambda: self.write(", "), self.traverse, node.elts)
	else:
	# `{}` would be interpreted as a dictionary literal, and
	# `set` might be shadowed. Thus:
	self.write('{*()}')

	def visit_Dict(self, node):
	def write_key_value_pair(k, v):
	self.traverse(k)
	self.write(": ")
	self.traverse(v)

	def write_item(item):
	k, v = item
	if k is None:
	# for dictionary unpacking operator in dicts {**{'y': 2}}
	# see PEP 448 for details
	self.write("**")
	self.set_precedence(_Precedence.EXPR, v)
	self.traverse(v)
	else:
	write_key_value_pair(k, v)

	with self.delimit("{", "}"):
	self.interleave(
	lambda: self.write(", "), write_item, zip(node.keys, node.values)
	)

	def visit_Tuple(self, node):
	with self.delimit("(", ")"):
	self.items_view(self.traverse, node.elts)

	unop = {"Invert": "~", "Not": "not", "UAdd": "+", "USub": "-"}
	unop_precedence = {
	"not": _Precedence.NOT,
	"~": _Precedence.FACTOR,
	"+": _Precedence.FACTOR,
	"-": _Precedence.FACTOR,
	}

	def visit_UnaryOp(self, node):
	operator = self.unop[node.op.__class__.__name__]
	operator_precedence = self.unop_precedence[operator]
	with self.require_parens(operator_precedence, node):
	self.write(operator)
	# factor prefixes (+, -, ~) shouldn't be seperated
	# from the value they belong, (e.g: +1 instead of + 1)
	if operator_precedence is not _Precedence.FACTOR:
	self.write(" ")
	self.set_precedence(operator_precedence, node.operand)
	self.traverse(node.operand)

	binop = {
	"Add": "+",
	"Sub": "-",
	"Mult": "*",
	"MatMult": "@",
	"Div": "/",
	"Mod": "%",
	"LShift": "<<",
	"RShift": ">>",
	"BitOr": "\|",
	"BitXor": "^",
	"BitAnd": "&",
	"FloorDiv": "//",
	"Pow": "**",
	}

	binop_precedence = {
	"+": _Precedence.ARITH,
	"-": _Precedence.ARITH,
	"*": _Precedence.TERM,
	"@": _Precedence.TERM,
	"/": _Precedence.TERM,
	"%": _Precedence.TERM,
	"<<": _Precedence.SHIFT,
	">>": _Precedence.SHIFT,
	"\|": _Precedence.BOR,
	"^": _Precedence.BXOR,
	"&": _Precedence.BAND,
	"//": _Precedence.TERM,
	"**": _Precedence.POWER,
	}

	binop_rassoc = frozenset(("**",))
	def visit_BinOp(self, node):
	operator = self.binop[node.op.__class__.__name__]
	operator_precedence = self.binop_precedence[operator]
	with self.require_parens(operator_precedence, node):
	if operator in self.binop_rassoc:
	left_precedence = operator_precedence.next()
	right_precedence = operator_precedence
	else:
	left_precedence = operator_precedence
	right_precedence = operator_precedence.next()

	self.set_precedence(left_precedence, node.left)
	self.traverse(node.left)
	self.write(f" {operator} ")
	self.set_precedence(right_precedence, node.right)
	self.traverse(node.right)

	cmpops = {
	"Eq": "==",
	"NotEq": "!=",
	"Lt": "<",
	"LtE": "<=",
	"Gt": ">",
	"GtE": ">=",
	"Is": "is",
	"IsNot": "is not",
	"In": "in",
	"NotIn": "not in",
	}

	def visit_Compare(self, node):
	with self.require_parens(_Precedence.CMP, node):
	self.set_precedence(_Precedence.CMP.next(), node.left, *node.comparators)
	self.traverse(node.left)
	for o, e in zip(node.ops, node.comparators):
	self.write(" " + self.cmpops[o.__class__.__name__] + " ")
	self.traverse(e)

	boolops = {"And": "and", "Or": "or"}
	boolop_precedence = {"and": _Precedence.AND, "or": _Precedence.OR}

	def visit_BoolOp(self, node):
	operator = self.boolops[node.op.__class__.__name__]
	operator_precedence = self.boolop_precedence[operator]

	def increasing_level_traverse(node):
	nonlocal operator_precedence
	operator_precedence = operator_precedence.next()
	self.set_precedence(operator_precedence, node)
	self.traverse(node)

	with self.require_parens(operator_precedence, node):
	s = f" {operator} "
	self.interleave(lambda: self.write(s), increasing_level_traverse, node.values)

	def visit_Attribute(self, node):
	self.set_precedence(_Precedence.ATOM, node.value)
	self.traverse(node.value)
	# Special case: 3.__abs__() is a syntax error, so if node.value
	# is an integer literal then we need to either parenthesize
	# it or add an extra space to get 3 .__abs__().
	if isinstance(node.value, Constant) and isinstance(node.value.value, int):
	self.write(" ")
	self.write(".")
	self.write(node.attr)

	def visit_Call(self, node):
	self.set_precedence(_Precedence.ATOM, node.func)
	self.traverse(node.func)
	with self.delimit("(", ")"):
	comma = False
	for e in node.args:
	if comma:
	self.write(", ")
	else:
	comma = True
	self.traverse(e)
	for e in node.keywords:
	if comma:
	self.write(", ")
	else:
	comma = True
	self.traverse(e)

	def visit_Subscript(self, node):
	def is_simple_tuple(slice_value):
	# when unparsing a non-empty tuple, the parentheses can be safely
	# omitted if there aren't any elements that explicitly requires
	# parentheses (such as starred expressions).
	return (
	isinstance(slice_value, Tuple)
	and slice_value.elts
	and not any(isinstance(elt, Starred) for elt in slice_value.elts)
	)

	self.set_precedence(_Precedence.ATOM, node.value)
	self.traverse(node.value)
	with self.delimit("[", "]"):
	if is_simple_tuple(node.slice):
	self.items_view(self.traverse, node.slice.elts)
	else:
	self.traverse(node.slice)

	def visit_Starred(self, node):
	self.write("*")
	self.set_precedence(_Precedence.EXPR, node.value)
	self.traverse(node.value)

	def visit_Ellipsis(self, node):
	self.write("...")

	def visit_Slice(self, node):
	if node.lower:
	self.traverse(node.lower)
	self.write(":")
	if node.upper:
	self.traverse(node.upper)
	if node.step:
	self.write(":")
	self.traverse(node.step)

	def visit_arg(self, node):
	self.write(node.arg)
	if node.annotation:
	self.write(": ")
	self.traverse(node.annotation)

	def visit_arguments(self, node):
	first = True
	# normal arguments
	all_args = node.posonlyargs + node.args
	defaults = [None] * (len(all_args) - len(node.defaults)) + node.defaults
	for index, elements in enumerate(zip(all_args, defaults), 1):
	a, d = elements
	if first:
	first = False
	else:
	self.write(", ")
	self.traverse(a)
	if d:
	self.write("=")
	self.traverse(d)
	if index == len(node.posonlyargs):
	self.write(", /")

	# varargs, or bare '*' if no varargs but keyword-only arguments present
	if node.vararg or node.kwonlyargs:
	if first:
	first = False
	else:
	self.write(", ")
	self.write("*")
	if node.vararg:
	self.write(node.vararg.arg)
	if node.vararg.annotation:
	self.write(": ")
	self.traverse(node.vararg.annotation)

	# keyword-only arguments
	if node.kwonlyargs:
	for a, d in zip(node.kwonlyargs, node.kw_defaults):
	self.write(", ")
	self.traverse(a)
	if d:
	self.write("=")
	self.traverse(d)

	# kwargs
	if node.kwarg:
	if first:
	first = False
	else:
	self.write(", ")
	self.write("**" + node.kwarg.arg)
	if node.kwarg.annotation:
	self.write(": ")
	self.traverse(node.kwarg.annotation)

	def visit_keyword(self, node):
	if node.arg is None:
	self.write("**")
	else:
	self.write(node.arg)
	self.write("=")
	self.traverse(node.value)

	def visit_Lambda(self, node):
	with self.require_parens(_Precedence.TEST, node):
	self.write("lambda ")
	self.traverse(node.args)
	self.write(": ")
	self.set_precedence(_Precedence.TEST, node.body)
	self.traverse(node.body)

	def visit_alias(self, node):
	self.write(node.name)
	if node.asname:
	self.write(" as " + node.asname)

	def visit_withitem(self, node):
	self.traverse(node.context_expr)
	if node.optional_vars:
	self.write(" as ")
	self.traverse(node.optional_vars)

	def unparse(ast_obj):
	unparser = _Unparser()
	return unparser.visit(ast_obj)


	def main():
	import argparse

	parser = argparse.ArgumentParser(prog='python -m ast')
	parser.add_argument('infile', type=argparse.FileType(mode='rb'), nargs='?',
	default='-',
	help='the file to parse; defaults to stdin')
	parser.add_argument('-m', '--mode', default='exec',
	choices=('exec', 'single', 'eval', 'func_type'),
	help='specify what kind of code must be parsed')
	parser.add_argument('--no-type-comments', default=True, action='store_false',
	help="don't add information about type comments")
	parser.add_argument('-a', '--include-attributes', action='store_true',
	help='include attributes such as line numbers and '
	'column offsets')
	parser.add_argument('-i', '--indent', type=int, default=3,
	help='indentation of nodes (number of spaces)')
	args = parser.parse_args()

	with args.infile as infile:
	source = infile.read()
	tree = parse(source, args.infile.name, args.mode, type_comments=args.no_type_comments)
	print(dump(tree, include_attributes=args.include_attributes, indent=args.indent))

	if __name__ == '__main__':
	main()

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2021	2022	2025