code: def CopyToDateTimeString(self):
      
      if self._number_of_seconds is None or self.fraction_of_second is None:
        return None
  
      precision_helper = precisions.PrecisionHelperFactory.CreatePrecisionHelper(
          self._precision)
  
      return precision_helper.CopyToDateTimeString(
          self._time_elements_tuple, self.fraction_of_second)
docs: Copies the time elements to a date and time string.
  
      Returns:
        str: date and time value formatted as: "YYYY-MM-DD hh:mm:ss" or
            "YYYY-MM-DD hh:mm:ss.######" or None if time elements are missing.
  
      Raises:
        ValueError: if the precision value is unsupported.