https://ja.m.wikipedia.org/wiki/%E6%9C%9D%E9%AE%AE%E6%B0%91%E4%B8%BB%E4%B8%BB%E7%BE%A9%E4%BA%BA%E6%B0%91%E5%85%B1%E5%92%8C%E5%9B%BD%E3%81%AE%E3%82%A4%E3%83%B3%E3%82%BF%E3%83%BC%E3%83%8D%E3%83%83%E3%83%88
思考の /dev/null
