code: def ancestors(self, definition: Union[SLOT_OR_SLOTNAME,
                                            CLASS_OR_CLASSNAME]) \
              -> List[Union[SlotDefinitionName, ClassDefinitionName]]:
          
          definition = self.obj_for(definition)
          if definition is not None:
              return [definition.name] + self.ancestors(definition.is_a)
          else:
              return []
docs: Return an ordered list of ancestor names for the supplied slot or class
  
          @param definition: Slot or class name or definition
          @return: List of ancestor names