anchor.diff:    final int port;
     final String username;
     final String password;
  -  final ErrorHandler onError;
   
     Socket _socket;
     StreamIterator<String> _responses;
  
positive.code:       socket.encoding = UTF8;
        socket.write('$username\x0d$password\x0d');
        await socket.flush();
        responses = new StreamIterator<String>(_socket.transform(UTF8.decoder).transform(const LineSplitter()));
        await responses.moveNext();
        if (responses.current != 'Login:')
          throw new TelevisionException('did not get login prompt', responses.current, this);
  
negative.code: class Television {
    Television({
      this.host,
      this.port: 10002,
      this.username,
      this.password,
    }) {
      assert(port != null);
    }
  