anchor.diff:      if (_isolate != null) {
         throw new StateError('Cannot listen to the same channel more than once.');
       }
  -    receivePort = new ReceivePort();
  +    _receivePort = new ReceivePort();
       if (onError != null) {
  -      errorPort = new ReceivePort();
  -      errorPort.listen((error) {
  +      _errorPort = new ReceivePort();
  +      _errorPort.listen((error) {
           onError(error);
         });
       }
       if (onDone != null) {
  -      exitPort = new ReceivePort();
  -      exitPort.listen((_) {
  +      _exitPort = new ReceivePort();
  +      _exitPort.listen((_) {
           onDone();
         });
       }
       _isolate = await Isolate.spawnUri(
  -        pluginUri, <String>[], receivePort.sendPort,
  -        onError: errorPort?.sendPort,
  -        onExit: exitPort?.sendPort,
  +        pluginUri, <String>[], _receivePort.sendPort,
  +        onError: _errorPort?.sendPort,
  +        onExit: _exitPort?.sendPort,
           packageConfig: packagesUri);
       Completer<Null> channelReady = new Completer<Null>();
  -    receivePort.listen((dynamic input) {
  +    _receivePort.listen((dynamic input) {
         if (input is SendPort) {
   //        print('[server] Received send port');
           _sendPort = input;
  
positive.code:    */
    SendPort _sendPort;
  
    ReceivePort receivePort;
  
    ReceivePort errorPort;
  
    ReceivePort exitPort;
  
    /**
     * Initialize a newly created channel to communicate with an isolate running
  
negative.code:       this.pluginUri, this.packagesUri, this.instrumentationService);
    @override
    void close() {
      _receivePort?.close();
      _errorPort?.close();
      _exitPort?.close();
      _isolate = null;
    }
  
    @override
  