code: def save_token(self, access_token):
          
          self.access_tokens[access_token.token] = access_token
  
          unique_token_key = self._unique_token_key(access_token.client_id,
                                                    access_token.grant_type,
                                                    access_token.user_id)
  
          self.unique_token_identifier[unique_token_key] = access_token.token
  
          if access_token.refresh_token is not None:
              self.refresh_tokens[access_token.refresh_token] = access_token
  
          return True
docs: Stores an access token and additional data in memory.
  
          :param access_token: An instance of :class:`oauth2.datatype.AccessToken`.