// multiple connections may be served concurrently.
		go func(c net.Conn) {
			// Echo all incoming data.
			io.Copy(c, c)
			// Shut down the connection.
			c.Close()
		}(conn)
	}
}

func ExampleDialer() {
	var d net.Dialer
	ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
	defer cancel()

	conn, err := d.DialContext(ctx, "tcp", "localhost:12345")
	if err != nil {