Python---类的内置方法

https://www.cnblogs.com/zzzlw/p/9286828.html

https://www.cnblogs.com/Presley-lpc/p/9903300.html

https://blog.csdn.net/henku449141932/article/details/80838660

https://blog.csdn.net/panda996/article/details/84791609

https://blog.51cto.com/ljbaby/2348736

http://python.jobbole.com/87239/