code: def CopyToDateTimeString(self):
      
      if self._number_of_seconds is None:
        return None
  
      return '{0:04d}-{1:02d}-{2:02d} {3:02d}:{4:02d}:{5:02d}'.format(
          self._time_elements_tuple[0], self._time_elements_tuple[1],
          self._time_elements_tuple[2], self._time_elements_tuple[3],
          self._time_elements_tuple[4], self._time_elements_tuple[5])
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 None
            if time elements are missing.