anchor.diff:    }
   }
   
  -class _DemoMapper extends FutureValue<core.Coordinate, int> {
  -  Future<int> getFuture(value) {
  -    final sendPort = spawnFunction(_demoIsolate);
  -    return sendPort.call(value);
  -  }
  +class _DemoValue extends SendPortValue<core.Coordinate, int> {
  +  _DemoValue() : super(spawnFunction(_demoIsolate));
   }
   
   void _demoIsolate() {
  -  port.receive((core.Coordinate input,
  -      SendPort reply) {
  -
  +  new SendValuePort<core.Coordinate, int>((input) {
       final start = new Date.now();
       Duration delta;
       do {
  
positive.code:   final Stage _stage;
    final core.AffineTransform _tx;
    final Dragger _dragger;
    final _DemoMapper _demoMapper;
  
    core.Coordinate _mouseLocation;
    bool _frameRequested = false;
  
negative.code:     } while(delta.inSeconds < 1);
  
      final int output = input.x * input.y;
      return output;
    });
  }
  