anchor.diff:      demo.value = input.value;
     });
   
  -  demo.updated.listen((args) {
  +  demo.output.listen((data) {
       input.style.background = '';
  -  });
  -
  -  demo.error.listen((args) {
  +  }, onError: (error) {
       input.style.background = 'red';
     });
   }
  
positive.code:   void _update() {
      final t = [_typeNumber, _errorCorrectLevel, _value];
  
      _qrMapper.input = t;
    }
  
    void _onFrame(double highResTime){
  
negative.code: import 'dart:html';
  import 'dart:async';
  import 'dart:math' as math;
  import 'package:bot/bot.dart';
  import 'package:bot_web/bot_html.dart';
  import 'package:qr/qr.dart';
  import 'package:qr/src/send_port_value.dart';
  
  void main() {
    final CanvasElement canvas = querySelector("#content");
    final DivElement typeDiv = querySelector('#type-div');
    final DivElement errorDiv = querySelector('#error-div');
  