anchor.diff:    }
   
     updateView() {
  -    updateRoot(vRoot(type: 'Counter')(elapsedSeconds));
  +    updateRoot(vRoot(type: 'Counter')([
  +      vElement('div')(elapsedSeconds),
  +      vElement('input', attrs: const {Attr.type: 'text'})
  +    ]));
     }
   }
   
  
positive.code: 
    updateView() {
      updateRoot(vRoot()([
        vElement('button', type: 'MoveButton')('Move'),
        vComponent($Box, data: new BoxData(_anchor, position == 0)),
        vComponent($Box, data: new BoxData(_anchor, position == 1)),
        vComponent($Box, data: new BoxData(_anchor, position == 2))
  
negative.code:   Anchor _anchor = new Anchor();
  
    init() {
      new Timer.periodic(new Duration(seconds: 1), (t) {
        position = (position + 1) % 3;
        invalidate();
      });
  