is&==

is:判断两个变量的id是否相等

==：判断两个变量的值是否相等

>>> s1 = 'ryan is my hero'
>>> s2 = 'ryan is my hero'
>>> print(s1==s2)
True
>>> print(id(s1),id(s2))
1499122832304 1499122840432

　>>> print(s1 is s2)
　False