ubuntu 18安装Python3.7
https://zhuanlan.zhihu.com/p/129867344
实例属性查找
https://www.cnblogs.com/raind/p/10146160.html
https://www.jianshu.com/p/26174db49172
迭代器
https://www.runoob.com/python3/python3-iterator-generator.html
https://www.liaoxuefeng.com/wiki/1016959663602400/1017323698112640
https://wiki.jikexueyuan.com/project/explore-python/Advanced-Features/generator.html
https://www.liujiangblog.com/course/python/37