anchor.diff:      pumpEventQueue().then((_) {
         responseController.addError(new NoResponseException(request));
       });
  -    return responseController.stream.firstWhere((response) {
  -      return response.id == id;
  -    });
  +    return new Future<Response>(() =>
  +        responseController.stream.firstWhere((response) => response.id == id));
     }
   }
   
  
positive.code:   Future close([int code, String reason]) =>
        controller.close().then((_) => twin.controller.close());
  
    StreamSubscription<T> listen(void onData(T event),
            {Function onError, void onDone(), bool cancelOnError}) =>
        stream.listen(onData,
            onError: onError, onDone: onDone, cancelOnError: cancelOnError);
  
    noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
  
    Stream<T> where(bool test(T t)) => stream.where(test);
  }
  
  class MockSource extends StringTypedMock implements Source {
  
negative.code:     return socket1;
    }
  
    void add(dynamic text) => controller.add(text as T);
  
    void allowMultipleListeners() {
      stream = stream.asBroadcastStream();
  