anchor.diff:    final Stage _stage;
     final core.AffineTransform _tx;
     final Dragger _dragger;
  -  final _DemoMapper _demoMapper;
  +  final _DemoValue _demoMapper;
   
     core.Coordinate _mouseLocation;
     bool _frameRequested = false;
  
positive.code:   }
  
    DraggerDemo._internal(this._canvas, this._stage, this._tx, this._dragger) :
      _demoMapper = new _DemoMapper() {
      _canvas.on.mouseMove.add(_canvas_mouseMove);
      _canvas.on.mouseOut.add(_canvas_mouseOut);
      _dragger.dragDelta.add(_onDrag);
  
negative.code:     } while(delta.inSeconds < 1);
  
      final int output = input.x * input.y;
      return output;
    });
  }
  