python：迭代器协议实现斐波那契数列

#迭代器协议实现斐波那契数列
class Fib:
    def __init__(self):
        self._n=1
        self._m=1

    def __iter__(self):
        return self

    def __next__(self):
        self._n,self._m=self._m,self._n+self._m
        return self._n


f=Fib()
print(f.__next__())
print(f.__next__())
print(f.__next__())
print(f.__next__())