for else

for else主要是看for循环里是否有满足条件的情况，如果没有执行break，肯定会执行else

for i in range(3):
    if i==3:
        print(i)
        break
else:
    print("else")
>>else

for i in range(3):
    if i==2:
        print(i)
        break
else:
    print("else")
>>2