docs: def round_to(self, dt, hour, minute, second, mode="floor"):
          """Round the given datetime to specified hour, minute and second.
  
          :param mode: 'floor' or 'ceiling'
  
          **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。
          """
          mode = mode.lower()
  
          new_dt = datetime(dt.year, dt.month, dt.day, hour, minute, second)
          if mode == "floor":
              if new_dt <= dt:
                  return new_dt
              else:
                  return rolex.add_days(new_dt, -1)
          elif mode == "ceiling":
              if new_dt >= dt:
                  return new_dt
              else:
                  return rolex.add_days(new_dt, 1)
          else:
              raise ValueError("'mode' has to be 'floor' or 'ceiling'!")