python while for 语句

while 语句：

>>> x = 1
>>> while x < 5:
...     x +=1
...     print(x)
...     
2
3
4
5

for 语句：

>>> words = ['aaa','bbb', 'ccc']
>>> for word in words:
...     print(word)
...     
aaa
bbb
ccc