https://blog.wongcw.com/2021/10/30/%e5%be%ae%e8%bb%9f%ef%bc%9a%e6%94%b6%e8%b3%bc%e5%85%a7%e5%ae%b9%e5%af%a9%e6%a0%b8%e8%a7%a3%e6%b1%ba%e6%96%b9%e6%a1%88%e4%be%9b%e6%87%89%e5%95%86two-hat/