Singleton class python3

# coding:utf-8
class Singleton():
    __instance = None

    def __init__(self):
        print("我是init方法.")

    def __new__(cls):
        if not Singleton.__instance:
            Singleton.__instance = object.__new__(cls)
        return Singleton.__instance

obj1 = Singleton()
obj2 = Singleton()
print(id(obj1), id(obj2))

执行结果:
I init method. 
I init method. 
1,227,006,412,270,064