一串字符

#_*_coding:utf-8_*_

 age = 3
 name = "Tom"
 print("{0} was {1} years old".format(name, age))

 print(name + " was " + str(age) + " years old")

常量不会被修改,直接以字面意义使用它们

不能以数字开头
区别大小写
可以是字母 数字  和下划线

#

缩进代表语句块

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