def pay_onetime(self, **kwargs):
        url = '{}subscribe/payments/onetime'.format(self.imp_url)
        for key in ['merchant_uid', 'amount', 'card_number', 'expiry', 'birth', 'pwd_2digit']:
            if kwargs not in key:
                raise KeyError('Essential parameter is missing!: %s' % key)

        return self._post(url, kwargs)
dataset/ETHPy150Open iamport/iamport-rest-client-python/iamport/client.py/Iamport.pay_onetime/swapped operands of `not in`