code: def add(self, key, content, **metadata):
          
          self.members.add(key)
          document_hash = self._get_hash(key)
          document_hash.update(content=content, **metadata)
  
          for word, score in self.tokenizer.tokenize(content).items():
              word_key = self.get_key(word)
              word_key[key] = -score
docs: :param key: Document unique identifier.
          :param str content: Content to store and index for search.
          :param metadata: Arbitrary key/value pairs to store for document.
  
          Add a document to the search index.