Python判断字符串是否符合某一正则表达式

#encode:u8

import re

s1 = 'adkkdk'

#判断s1字符串是否负责都为小写的正则
an = re.search('^[a-z]+$', s1)
if an:
	print 'yes'
else:
	print 'no'
#encode:u8

import re

s1 = 'adkkd