type changeImplConn struct {
	net.Conn
	writeFunc func([]byte) (int, error)
	closeFunc func() error
}

func (w *changeImplConn) Write(p []byte) (n int, err error) {
	if w.writeFunc != nil {
		return w.writeFunc(p)
	}
	return w.Conn.Write(p)
}

func (w *changeImplConn) Close() error {
	if w.closeFunc != nil {
		return w.closeFunc()
	}
	return w.Conn.Close()
}