code: def _run_once(runner_list, extra_tick, use_poll):
      
      if len(runner_list) > 0:
          asyncore.loop(0, use_poll, None, 1)
          for runner in runner_list:
              if not runner.tick():
                  return runner
      if extra_tick is not None:
          code = extra_tick()
          if code is False:
              return False
      return True
docs: :return True - success; False - extra_tick failure; runner object - the runner who tick failure