说明：  python练习。Python是一种跨平台的计算机程序设计语言。 是一个高层次的结合了解释性、编译性、互动性和面向对象的脚本语言。最初被设计用于编写自动化脚本(shell)，随着版本的不断更新和语言新功能的添加，越多被用于独立的、大型项目的开发。
(Python is a cross platform computer programming language. It is a high-level script language which combines interpretability, compiler, interactivity and object-oriented. Originally designed to write automated scripts (shells), with the continuous updating of versions and the addition of new language features, more and more are used for independent, large-scale project development.)