def instance_url(self):
        token = util.utf8(self.id)
        extn = urllib.quote_plus(token)

        if (hasattr(self, 'customer')):
            customer = util.utf8(self.customer)
            base = Customer.class_url()
            cust_extn = urllib.quote_plus(customer)
            return (base, cust_extn, extn) % "%s/%s/sources/%s"
        else:
            base = BitcoinReceiver.class_url()
            return "%s/%s" % (base, extn)
dataset/ETHPy150Open stripe/stripe-python/stripe/resource.py/BitcoinReceiver.instance_url/swapped operands of `%`