Perform bulk add of list members from user ID or screenname

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