anchor.diff:    }
   
     /// Write as a string
  -  Future<bool> writeString(String data){
  +  Future writeString(String data){
       _checkOpen();
       final completer = new Completer<bool>();
       final replyPort = new ReceivePort();
       _servicePort.send([replyPort.sendPort, _WRITE_METHOD, _ttyFd, data]);
       replyPort.first.then((result) {
         if (result[0] == null) {
  -        completer.complete(true);
  +        completer.complete();
         } else {
           completer.completeError("Cannot write in $portname : ${result[0]}");
         }
  
positive.code:     replyPort.first.then((List result) {
        if (result[0] == null) {
          _ttyFd = -1;
          completer.complete(true);
        } else {
          completer.completeError("Cannot close $portname : ${result[0]}");
        }
  
negative.code:   int get fd => _ttyFd;
  
    /// Close the connection.
    Future close(){
      _checkOpen();
      final completer = new Completer<bool>();
      final replyPort = new ReceivePort();
  