code: def add_phrase(self,
                     phrase: List[int]) -> None:
          
          if len(phrase) == 1:
              self.final_ids.add(phrase[0])
          else:
              next_word = phrase[0]
              if next_word not in self.children:
                  self.children[next_word] = AvoidTrie()
              self.step(next_word).add_phrase(phrase[1:])
docs: Recursively adds a phrase to this trie node.
  
          :param phrase: A list of word IDs to add to this trie node.