https://blog.wongcw.com/2021/12/15/%e5%85%a8%e6%96%b0%e6%9c%ac%e7%94%b0%e6%80%9d%e5%9f%9ftype-r%e9%a0%90%e5%91%8a%e5%9c%96%e7%99%bc%e4%bd%88-%e6%9c%aa%e4%be%86%e5%be%88%e6%9c%89%e5%8f%af%e8%83%bd%e9%80%b2%e5%85%a5%e5%9c%8b%e5%85%a7/