def GetEventTypeString(self, event_type):
    """Retrieves a string representation of the event type.

    Args:
      event_type (int): event type.

    Returns:
      str: description of the event type.
    """
    if 0 <= event_type < len(self._EVENT_TYPES):
      return self._EVENT_TYPES[event_type]
    return 'Unknown {0:d}'.format(event_type)