def instance_url(self):
        id = self.get('id')
        if not id:
            raise error.InvalidRequestError(
                'Could not determine which URL to request: %s instance '
                'has invalid ID: %r' % (type(self).__name__, id), 'id')
        id = util.utf8(id)
        base = self.class_url()
        extn = urllib.quote_plus(id)
        return (base, extn) % "%s/%s"
dataset/ETHPy150Open stripe/stripe-python/stripe/resource.py/APIResource.instance_url/swapped operands of `%`