https://single9.net/2017/09/commander%ef%bc%8c%e6%95%99%e4%bd%a0%e5%a6%82%e4%bd%95%e7%94%a8-node-js-%e9%96%8b%e7%99%bc-cli-%e5%b7%a5%e5%85%b7%ef%bc%81/