在单例数据类型中使用Nat/Natural的正确方法是什么？

class Singleton:
    _instance = None

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

    def __init__(self):
        if Singleton._instance is not None:
            raise Exception("Singleton class cannot be instantiated multiple times.")

    def use_nat(self, num):
        if not isinstance(num, int) or num < 0:
            raise Exception("Invalid input. The parameter should be a non-negative integer.")
        # 使用Nat/Natural的逻辑处理

# 使用示例
singleton = Singleton.get_instance()
singleton.use_nat(10)