anchor.diff:  }
   
   main() async {
  -  var pool = await createWorkerPool(4, testWorker).initAll();
  -  
  -  pool.sendAll("Hello World");
  -  
  -  await pool.stopAll();
  +  var pool = await createWorkerPool(20, testWorker).init();
  +  
  +  pool.send("Hello World");
  +  
  +  await pool.stop();
   }
positive.code:   
    WorkerPool(this.sockets);
    
    Future waitForAll() {
      return Future.wait(sockets.map((it) => it.waitFor()).toList());
    }
    
    Future stopAll() {
      return Future.wait(sockets.map((it) => it.stop()).toList());
    }
    
    Future pingAll() {
      return Future.wait(sockets.map((it) => it.ping()).toList());
    }
    
    void sendAll(dynamic data) {
      forEach((socket) => socket.send(data));
    }
    
    void listenAll(void handler(int worker, event)) {
      var i = 0;
      for (var worker in sockets) {
        var id = i;
  
negative.code:     }
    }
    
    Future<WorkerPool> init() => Future.wait(sockets.map((it) => it.init()).toList()).then((_) => this);
    
    void forEach(void handler(WorkerSocket socket)) {
      sockets.forEach(handler);
  