为何：combinatios = product(l1, l2) 打印出错，而for n in product(a, b):不会？

from itertools import product
l1 = [1, 2, 3]
l2 = [4, 5, 6]
combinatios = product(l1, l2)
print(combinatios)

.product object at 0xac696be8>
[程序已完成]

from itertools import product

a = [1, 2, 3]
b = [4, 5, 6]
for n in product(a, b):
    print(n)
# 代码运行正确！

并没有错，combinatios就是个product对象