For P'Fai

import re
import sys
import os

if len(sys.argv) != 2:
    print 'Error: need to specify a path to the directory as an argument'
    sys.exit(1)

fpath = sys.argv[1]
os.chdir(fpath)

def get_text_and_group():
    text = raw_input('>>> Please input "text": ')
    group = raw_input('>>> Please input "group": ')
    return {'text': text, 'group': group}

def f1(content, text, group):
    return re.subn(
        '(?m)(?<!</group>\s)<text>{}</text>'.format(re.escape(text)),
        '<group>{}</group>\n<text>{}</text>'.format(group, text),
        content
    )

def f2(content, text, group):
    return re.subn(
        '</instance>',
        '''<label>
<group>{}</group>
<text>{}</text>
</label>
</instance>'''.format(group, text),
        content
    )

def runner(fun, data):
    all_changes = 0
    for f in os.listdir('.'):
        if f.endswith('.xml'):
            print "Processing {}".format(f)
            with open(f) as fp:
                content = fp.read().replace('\x00', '').replace('\r', '\n')[2:]
            content, changes = fun(content, **data)
            all_changes += changes
            print "Number of changes made to the file: {}".format(changes)
            if changes:
                with open(f, 'w') as fp:
                    fp.write(content)
    print "All changes made: {}".format(all_changes)

while True:
    print '=== Menu ==='
    print '1) Add a group when given a text'
    print '2) Add a label to all instances'
    print '3) Exit'
    ch = raw_input('>>> Please input the mode that you want to operate: ')
    if ch == '1':
        print "==== Mode: Add a group when given a text ===="
        runner(f1, get_text_and_group())
    elif ch == '2':
        print "==== Add a label to all instances ===="
        runner(f2, get_text_and_group())
    elif ch == '3':
        sys.exit(0)
    else:
        print 'Invalid response. Try again\n'