anchor.diff:    Future onceIsolateReady;
   
     _IsolateHandler() {
  +    onIsolateMessage = _messageController.stream;
  +    onceIsolateReady = _readyController.stream.first;
  +    _startIsolate();
  +
       // TODO(ericarnold): Implement
     }
   
  
positive.code: 
    // Fired when isolate responds to message
    Stream<ServiceActionEvent> onIsolateResponse(String callId) {
      onIsolateMessage = _messageController.stream;
      onceIsolateReady = _readyController.stream.first;
      // TODO(ericarnold): Implement
    }
  
  
negative.code:     return completer.future;
    }
  
    Future _pong(int id) {
      Completer completer = _serviceCallCompleters[id];
      _serviceCallCompleters.remove(id);
      completer.complete("pong");
  