https://wenku.baidu.com/view/1cdb340b3a3567ec102de2bd960590c69ec3d8b8.html
https://blog.youkuaiyun.com/louishao/article/details/69879981
https://www.cnblogs.com/jeffkuang/articles/4859158.html
https://blog.youkuaiyun.com/column/details/pythonpil.html
https://blog.youkuaiyun.com/qq_32506555/article/details/74911271