def _FormatTag(self, event):
    """Formats the event tag.

    Args:
      event (EventObject): event.

    Returns:
      str: event tag field.
    """
    tag = getattr(event, 'tag', None)

    if not tag:
      return '-'

    return ' '.join(tag.labels)
Formats the event tag.

    Args:
      event (EventObject): event.

    Returns:
      str: event tag field.