code: def is_from_parent(cls, attribute_name, value=None):
      # type: (type, str, bool) -> bool
      
      if value is None:
          try:
              # Get the current value
              value = getattr(cls, attribute_name)
          except AttributeError:
              # No need to go further: the attribute does not exist
              return False
  
      for base in cls.__bases__:
          # Look for the value in each parent class
          try:
              return getattr(base, attribute_name) is value
          except AttributeError:
              pass
  
      # Attribute value not found in parent classes
      return False
docs: Tests if the current attribute value is shared by a parent of the given
      class.
  
      Returns None if the attribute value is None.
  
      :param cls: Child class with the requested attribute
      :param attribute_name: Name of the attribute to be tested
      :param value: The exact value in the child class (optional)
      :return: True if the attribute value is shared with a parent class