code: def CopyToDateTimeString(self):
      
      if self._timestamp is None:
        return None
  
      number_of_days, hours, minutes, seconds = self._GetTimeValues(
          self._timestamp)
  
      year, month, day_of_month = self._GetDateValues(number_of_days, 1970, 1, 1)
  
      if self.fraction_of_second is None:
        return '{0:04d}-{1:02d}-{2:02d} {3:02d}:{4:02d}:{5:02d}'.format(
            year, month, day_of_month, hours, minutes, seconds)
  
      if pytsk3.TSK_VERSION_NUM >= 0x040200ff:
        return '{0:04d}-{1:02d}-{2:02d} {3:02d}:{4:02d}:{5:02d}.{6:09d}'.format(
            year, month, day_of_month, hours, minutes, seconds,
            self.fraction_of_second)
  
      return '{0:04d}-{1:02d}-{2:02d} {3:02d}:{4:02d}:{5:02d}.{6:07d}'.format(
          year, month, day_of_month, hours, minutes, seconds,
          self.fraction_of_second)
docs: Copies the date time value 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
            YYYY-MM-DD hh:mm:ss.#########