python中is和== 的差別

is 是 如果兩個變數都指向同一個物件 就會return True

>>> 1000 is 10**3
False
>>> 1000 == 10**3
True

== 是 物件推斷變數為同一個

>>> "a" is "a"
True
>>> "aa" is "a" * 2
True
>>> x = "a"
>>> "aa" is x * 2
False
>>> "aa" is intern(x*2)
True