如何重置我的单例类的缓存数据？

class Singleton:
    __instance = None
    __cache = None

    @staticmethod
    def get_instance():
        if Singleton.__instance is None:
            Singleton()
        return Singleton.__instance

    def __init__(self):
        if Singleton.__instance is not None:
            raise Exception("This class is a singleton!")
        else:
            Singleton.__instance = self
            Singleton.__cache = {}

    def reset_cache(self):
        Singleton.__cache = {}  # 清空缓存数据

    def get_data(self, key):
        return Singleton.__cache.get(key)

    def set_data(self, key, value):
        Singleton.__cache[key] = value


# 使用示例
singleton = Singleton.get_instance()
singleton.set_data("key", "value")
print(singleton.get_data("key"))  # 输出: value

singleton.reset_cache()
print(singleton.get_data("key"))  # 输出: None