text: """
      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.
  """
  from _ast import *
  
  
  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, 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):
      """
      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.
      """
      def _format(node):
          if isinstance(node, AST):
              args = []
              keywords = annotate_fields
              for field in node._fields:
                  try:
                      value = getattr(node, field)
                  except AttributeError:
                      keywords = True
                  else:
                      if keywords:
                          args.append('%s=%s' % (field, _format(value)))
                      else:
                          args.append(_format(value))
              if include_attributes and node._attributes:
                  for a in node._attributes:
                      try:
                          args.append('%s=%s' % (a, _format(getattr(node, a))))
                      except AttributeError:
                          pass
              return '%s(%s)' % (node.__class__.__name__, ', '.join(args))
          elif isinstance(node, list):
              return '[%s]' % ', '.join(_format(x) for x in node)
          return repr(node)
      if not isinstance(node, AST):
          raise TypeError('expected AST, got %r' % node.__class__.__name__)
      return _format(node)
  
  
  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 \
             and hasattr(old_node, attr):
              setattr(new_node, attr, getattr(old_node, attr))
      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 not hasattr(node, 'end_lineno'):
                  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 not hasattr(node, 'end_col_offset'):
                  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:
              child.end_lineno = getattr(child, 'end_lineno', 0) + 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):
      """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:
          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",
                                PendingDeprecationWarning, 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=Index(value=Str(s=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
  
  
  # The following code is for backward compatibility.
  # It will be removed in future.
  
  def _getter(self):
      return self.value
  
  def _setter(self, value):
      self.value = value
  
  Constant.n = property(_getter, _setter)
  Constant.s = property(_getter, _setter)
  
  class _ABC(type):
  
      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',
  }
  