# -*- coding:utf-8 -*-
def demo():
    for i in range(4):
        yield i
g = demo()

g1 = (i for i in g)
# def func():
#     for i in g:
#         yield i
g2 = (i for i in g1)

print(list(g1))
print(list(g2)) #生成器已经被取出