#!/usr/bin/env python
     # encoding: utf-8
     #
     # Copyright (c) 2010 Doug Hellmann.  All rights reserved.
     #
     """Negative look behind assertion.
     """
     #end_pymotw_header
     
     import re
     
     address = re.compile(
         '''
         ^
     
         # An address: username@domain.tld
     
         [\w\d.+-]+       # username
     
         # Ignore noreply addresses
         (?<!noreply)
     
         @
         ([\w\d.]+\.)+    # domain name prefix
         (com|org|edu)    # limit the allowed top-level domains
     
         $
         ''',
         re.UNICODE | re.VERBOSE)
     
     candidates = [
         u'first.last@example.com',
         u'noreply@example.com',
         ]
     
     for candidate in candidates:
         print
         print 'Candidate:', candidate
         match = address.search(candidate)
         if match:
             print '  Match:', candidate[match.start():match.end()]
         else:
             print '  No match'