old_contents: LAMBDA = lambda: 0
  
  
  def is_lambda(fun):
      """
      Check whether the given function is a lambda function.
  
      .. testsetup::
  
          from spiderpig.func import is_lambda
  
      .. testcode::
  
          def not_lambda_fun(): ---------------------------------------------------------------------------------------------------------------------------------------------------------------- ---
          lambda_fun = lambda:
  
          print(
              is_lambda(not_lambda_fun),
              is_lambda(lambda_fun)
          )
      .. testoutput::
  
          False True
  
      Args:
          fun (function)
  
      Returns:
          bool: True if the given function is a lambda function, False otherwise
      """
      return isinstance(fun, type(LAMBDA)) and fun.__name__ == LAMBDA.__name__
  
  
  def function_name(function):
      if function is None:
          return None
      if is_lambda(function):
          raise Exception('The function can not be a lambda function.')
      return '{}.{}'.format(function.__module__, function.__qualname__)
  
new_contents: LAMBDA = lambda: 0
  
  
  def is_lambda(fun):
      """
      Check whether the given function is a lambda function.
  
          >>> def not_lambda_fun():
          ...     return None
          ...
          >>> lambda_fun = lambda: None
          ...
          >>> print(
          ...     is_lambda(not_lambda_fun),
          ...     is_lambda(lambda_fun)
          ... )
          ...
          False True
  
      Args:
          fun (function)
  
      Returns:
          bool: True if the given function is a lambda function, False otherwise
      """
      return isinstance(fun, type(LAMBDA)) and fun.__name__ == LAMBDA.__name__
  
  
  def function_name(function):
      if function is None:
          return None
      if is_lambda(function):
          raise Exception('The function can not be a lambda function.')
      return '{}.{}'.format(function.__module__, function.__qualname__)
  
subject: fix doc test