def reply(msg=None, img=None):
            if msg:
                resp = urllib2.urlopen(BASE_URL + 'sendMessage', urllib.urlencode({
                    'chat_id': str(chat_id),
                    'text': msg.encode('utf-8'),
                    'disable_web_page_preview': 'true',
                    'reply_to_message_id': str(message_id),
                })).read()
            elif img:
                resp = multipart.post_multipart(BASE_URL + 'sendPhoto', [
                    ('chat_id', str(chat_id)),
                    ('reply_to_message_id', str(message_id)),
                ], [
                    ('photo', 'image.jpg', img),
                ])
            else:
                logging.error('no msg or img specified')
                resp = None

            logging.info('send response:')
            logging.info(resp)

        if text.startswith('/'):
            if text == '/start':
                reply('Bot enabled')
                setEnabled(chat_id, True)
            elif text == '/stop':
                reply('Bot disabled')
                setEnabled(chat_id, False)
            elif text == '/image':
                img = Image.new('RGB', (512, 512))
                base = random.randint(0, 16777216)
                pixels = [base+i*j for i in range(512) for j in range(512)]  # generate sample image
                img.putdata(pixels)
                output = StringIO.StringIO()
                img.save(output, 'JPEG')
                reply(img=output.getvalue())
            else:
                reply('What command?')