Singleton Pattern in Python

singleton.py

class Singleton:
    __instance = None
    value = None

    def __new__(cls):
        if Singleton.__instance is None:
            Singleton.__instance = object.__new__(cls)
        return Singleton.__instance


instance_A = Singleton()
instance_A.value = 5
instance_B = Singleton()
instance_B.value = 8

print (instance_A.value, instance_B.value)