https://blog.wongcw.com/2021/12/25/%e6%9c%ac%e7%94%b0%e7%a2%ba%e8%aa%8d%e6%80%9d%e5%9f%9f-type-r-%e5%8e%9f%e5%9e%8b%e5%b0%87%e5%9c%a8%e6%98%8e%e5%b9%b4-1-%e6%9c%88%e4%ba%ae%e7%9b%b8/