code: def add_list_members(self, screen_name=None, user_id=None, slug=None,
                           list_id=None, owner_id=None, owner_screen_name=None):
          
          return self._add_list_members(list_to_csv(screen_name),
                                        list_to_csv(user_id),
                                        slug, list_id, owner_id,
                                        owner_screen_name)
docs: Perform bulk add of list members from user ID or screenname