code: def last_written_time(self):
      
      timestamp = self._pyregf_key.get_last_written_time_as_integer()
      if timestamp == 0:
        return dfdatetime_semantic_time.SemanticTime('Not set')
  
      return dfdatetime_filetime.Filetime(timestamp=timestamp)
docs: dfdatetime.DateTimeValues: last written time.