docs: def get_merged_filter(self):
          """
          Return merged filter from list of handlers
  
          :return: merged filter
          :rtype: :class:`~responsebot.models.TweetFilter`
          """
          track = set()
          follow = set()
  
          for handler in self.handlers:
              track.update(handler.filter.track)
              follow.update(handler.filter.follow)
  
          return TweetFilter(track=list(track), follow=list(follow))