anchor.diff:  
   class PingPongGame {
   
  -  PingPongGame.play()
  +  PingPongGame()
         : _ping = new ReceivePort(),
           _pingPort = _ping.toSendPort(),
           _pong = null,
  
positive.code: 
    static void main() {
      init();
      PingPongGame pingPongGame = new PingPongGame.play();
    }
  
    static var _run;
  
negative.code:       shutdown();
        Benchmark1.add_result((1.0 * _iterations * Benchmark1.MESSAGES) / time);
        if (Benchmark1.run() < Benchmark1.RUNS) {
          new PingPongGame();
        } else {
          print("PingPong: ", Benchmark1.get_result());
        }
  