code: def all_segs_matching_fts(self, fts):
          
          matching_segs = []
          for seg, pairs in self.segments:
              if set(fts) <= set(pairs):
                  matching_segs.append(seg)
          return sorted(matching_segs, key=lambda x: len(x), reverse=True)
docs: Return segments matching a feature mask, both as (value, feature)
          tuples (sorted in reverse order by length).
  
          Args:
              fts (list): feature mask as (value, feature) tuples.
  
          Returns:
              list: segments matching `fts`, sorted in reverse order by length