环境：Python 3.6

class Fabs(object):    def __init__(self,max):        self.max = max        self.n, self.a, self.b = 0,0,1            def __iter__(self):        return self        def next(self):        if self.n < self.max:            r = self.b            self.a,self.b = self.b, self.a+self.b            self.n = self.n+1            return r        raise StopIteration()

for key in Fabs(3):    print (key)

原因是 Python 3 中没有next(), 而是__next__(self) 代替