武沛齐:http://www.cnblogs.com/wupeiqi/articles/4276448.html
RUNOOB.com : https://www.runoob.com/python/python-built-in-functions.html
武沛齐:http://www.cnblogs.com/wupeiqi/articles/4276448.html
RUNOOB.com : https://www.runoob.com/python/python-built-in-functions.html