python迭代器的应用场景

#!/usr/bin/env python
# coding=utf-8
 
class Fibonacci(object):
    def __init__(self, all_num):
        self.all_num = all_num
        self.current_num = 0
        self.a = 0
        self.b = 1
    
    def __iter__(self):
        return self
 
    def __next__(self):
        if self.current_num < self.all_num:
            ret = self.a
            self.a, self.b = self.b, self.a + self.b
            self.current_num += 1
 
            return ret
        else:
            raise StopIteration
 
 
fibo = Fibonacci(10)
 
for num in fibo:
    print(num)