python中如何正确使用正则表达式的详细模式（Verbose mode expression)

import re 
 
address = re.compile('[\w\d.+-]+@([\w\d.]+\.)+(com|org|edu)') 
 
candidates = [ 
 u'first.last@example.com', 
 u'first.last+category@gmail.com', 
 u'valid-address@mail.example.com', 
 u'not-valid@example.foo', 
] 
 
for candidate in candidates: 
 match = address.search(candidate) 
 print('{:<30} {}'.format( 
 candidate, 'Matches' if match else 'No match') 
 )

#python 3.6 
#蔡军生 
#http://blog.csdn.net/caimouse/article/details/51749579 
# 
import re 
 
address = re.compile( 
 ''''' 
 [\w\d.+-]+ # username 
 @ 
 ([\w\d.]+\.)+ # domain name prefix 
 (com|org|edu) # TODO: support more top-level domains 
 ''', 
 re.VERBOSE) 
 
candidates = [ 
 u'first.last@example.com', 
 u'first.last+category@gmail.com', 
 u'valid-address@mail.example.com', 
 u'not-valid@example.foo', 
] 
 
for candidate in candidates: 
 match = address.search(candidate) 
 print('{:<30} {}'.format( 
 candidate, 'Matches' if match else 'No match'), 
 ) 

first.last@example.com  Matches
first.last+category@gmail.com Matches
valid-address@mail.example.com Matches
not-valid@example.foo  No match