# 单例模式 class B:     __instance = None     def __new__(cls, *args, **kwargs):         if cls.__instance is None:             obj = object.__new__(cls)             cls.__instance = obj         return cls.__instance     def __init__(self, name, age):         self.name = name         self.age = age     def func(self):         print(self.name) a = B('alex', 80)  # 实例化,传值 b = B('egon', 20)  # 实例化,覆盖值 print(a) print(b) print(a.name) print(b.name)