Find false use of variables in Drupal .po file

#!/usr/bin/python
# encoding: utf-8

import re, sys, polib

if len(sys.argv)==1:
    print 'Usage: filename'
    sys.exit(0)
else:
    filename = sys.argv[1]

# Open file
po = polib.pofile(filename)

for e in po:
    msgid = getattr(e, 'msgid')
    msgstr = getattr(e, 'msgstr')

    if msgstr != "" and re.search('(?P<varname>[@%!][a-z_-]{1,}).', msgid):
        # Found a possible variable
        match = re.findall('(?P<varname>[@%!][a-z_-]{1,})', msgid)
        for i in match:
            if re.search('%s[^a-z]|%s$'%(i,i),msgstr):
                #print "%s is correct" % (i)
                pass
            else:
                print ""
                print 'Variable %s has been changed' % (i)
                print u"msgid  → %s" % (msgid)
                print u"msgstr → %s" % (msgstr)
                print ""