docs: def string2time(text):
      """Return :class:`datetime.datetime` object from given string,
      or ``None`` if failed to translate."""
      length = len(TIME_FORMAT)
      result = None
      while length:
          try:
              result = datetime.strptime(text, TIME_FORMAT[:length])
          except:
              length -= 1
          else:
              break
      return result