code: def _FormatDescription(self, event):
      
      date_time_string = timelib.Timestamp.CopyToIsoFormat(
          event.timestamp, timezone=self._output_mediator.timezone)
      timestamp_description = event.timestamp_desc or 'UNKNOWN'
  
      message, _ = self._output_mediator.GetFormattedMessages(event)
      if message is None:
        data_type = getattr(event, 'data_type', 'UNKNOWN')
        raise errors.NoFormatterFound(
            'Unable to find event formatter for: {0:s}.'.format(data_type))
  
      description = '{0:s}; {1:s}; {2:s}'.format(
          date_time_string, timestamp_description,
          message.replace(self._DESCRIPTION_FIELD_DELIMITER, ' '))
      return self._SanitizeField(description)
docs: Formats the description.
  
      Args:
        event (EventObject): event.
  
      Returns:
        str: formatted description field.