docs: def rnd_datetime(start=datetime(1970, 1, 1), end=datetime.now()):
      """
      Generate a random datetime between ``start`` to ``end``.
  
      :param start: Left bound
      :type start: string or datetime.datetime, (default datetime(1970, 1, 1))
      :param end: Right bound
      :type end: string or datetime.datetime, (default datetime.now())
      :return: a datetime.datetime object
  
      **中文文档**
  
      随机生成一个位于 ``start`` 和 ``end`` 之间的时间。
      """
      start = parser.parse_datetime(start)
      end = parser.parse_datetime(end)
      _assert_correct_start_end(start, end)
      return _rnd_datetime(start, end)