class EchoClient {
    private final String host;
    private final int port;

    public EchoClient(String host, int port) {
        this.host = host;
        this.port = port;
    }

    public void start()
        throws Exception {<FILL_FUNCTION_BODY>}

    public static void main(String[] args)
            throws Exception {
        if (args.length != 2) {
            System.err.println("Usage: " + EchoClient.class.getSimpleName() +
                    " <host> <port>"
            );
            return;
        }

        final String host = args[0];
        final int port = Integer.parseInt(args[1]);
        new EchoClient(host, port).start();
    }
}

        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group)
                .channel(NioSocketChannel.class)
                .remoteAddress(new InetSocketAddress(host, port))
                .handler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    public void initChannel(SocketChannel ch)
                        throws Exception {
                        ch.pipeline().addLast(
                             new EchoClientHandler());
                    }
                });
            ChannelFuture f = b.connect().sync();
            f.channel().closeFuture().sync();
        } finally {
            group.shutdownGracefully().sync();
        }
    
<no_super_class>