https://blog.faceutil.com/2020/05/04/%ea%b8%b0%ed%83%80-%ec%8a%a4%ed%83%80%ed%81%ac%eb%9e%98%ed%94%84%ed%8a%b8-%ec%89%90%ec%96%b4%ec%9b%a8%ec%96%b4-%eb%af%b8%ec%85%98-precursor-%ec%84%a0%ea%b5%ac%ec%9e%90-by-marshall/