def __init__(self, name, host='127.0.0.1', port=27017):
        self.name = name
        self.host = host
        self.port = port
def expiration_datetime(self):
        """Datetime that the verification will expire. """
        days_good_for = settings.VERIFY_STUDENT["DAYS_GOOD_FOR"]
        return self.created_at + timedelta(days=days_good_for)