Django sms keyword

vies.py

def _split_message(message):
    wall = models.Wall.objects.all()
    if len(wall) == 1:
        keyword = str(wall[0].sms_keyword)
        message = message.replace(keyword, '').replace('  ', ' ')
        return keyword, message
    codes = re.search("(^|\s)(\w{3})(\s|$)", message)
    if codes == None:
        return None, None
    keyword = _get_keyword(codes)
    message = message.replace(keyword, '').replace('  ', ' ')
    return keyword, message.strip()

def _get_keyword(regexp):
    keyword = None
    for keyword in regexp.groups():
        if models.Wall.objects.filter(sms_keyword=keyword).exists():
            break
    return keyword