code: def round_to(dt, hour, minute, second, mode="round"):
      
      mode = mode.lower()
      if mode not in _round_to_options:
          raise ValueError(
              "'mode' has to be one of %r!" % list(_round_to_options.keys()))
      return _round_to_options[mode](dt, hour, minute, second)
docs: Round the given datetime to specified hour, minute and second.
  
      :param mode: 'floor' or 'ceiling'
  
      .. versionadded:: 0.0.5
  
          message
  
  
      **中文文档**
  
      将给定时间对齐到最近的一个指定了小时, 分钟, 秒的时间上。