https://blog.wongcw.com/2018/10/30/%e3%80%8amac%e6%95%99%e5%ad%b8%e3%80%8bmac%e4%b8%8d%e5%8f%af%e4%b8%8d%e7%9f%a5%e7%9a%84altoption%e5%bf%85%e6%ae%ba%e6%8a%80%e7%94%a8%e6%b3%95/