anchor.diff:  -record(state, {
             sub = undefined,
             iss = undefined,
  +          id = undefined,
             user_info = #{},
             credentials = [],
             sessions = []
  
positive.code: handle_info(_Info, State) ->
  	{noreply, State}.
  
  terminate(_Reason, _State) ->
      tts_user_mgr:remove_user_by_pid(self()),
  	ok.
  
  code_change(_OldVsn, State, _Extra) ->
  
negative.code: 
  %% gen_server.
  
  init([UserId]) ->
  	{ok, #state{id = UserId }, 5000}.
  
  handle_call({set_user_info,UserInfo}, _From, State) ->
      {reply, ok, State#state{user_info=UserInfo}};
  