2019-04-06 调用函数

Built-in Functions ：https://docs.python.org/3/library/functions.html  （内置函数）

Built-in Constants ：https://docs.python.org/3/library/constants.html

Built-in Types ：  https://docs.python.org/3/library/stdtypes.html

Built-in Exceptions ： https://docs.python.org/3/library/exceptions.html   

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