def populate_class_members(self, element_cls, prop_name):
        super(ZeroOrOne, self).populate_class_members(element_cls, prop_name)
        self._add_getter()
        self._add_creator()
        self._add_inserter()
        self._add_adder()
        self._add_get_or_adder()
        self._add_remover()
Returns the card type if valid else None.
dataset/ETHPy150Open python-openxml/python-docx/docx/oxml/xmlchemy.py/ZeroOrOne.populate_class_members--crossover with--dataset/ETHPy150Open spookylukey/django-paypal/paypal/pro/creditcard.py/CreditCard.verify