anchor.diff:      return completer.future;
     }
   
  -  // TODO rename sendString ?
  +  /// Write as a string
     Future<bool> writeString(String data){
       _checkOpen();
       final completer = new Completer<bool>();
  
positive.code: 
    SerialPort(this.portname, {this.baudrate : 9600, this.databits: 8});
  
    Future<bool> open() {
      if(_ttyFd != -1){
        throw new StateError("$portname is yet open.");
  
negative.code:     return completer.future;
    }
  
    /// Read data send from the serial port
    Stream<List<int>> get onRead {
      StreamController<String> controller = new StreamController();
      _onReadControllers.add(controller);
  