def verify(self, challenge):
        if not re.match("^[a-f0-9]{20,32}$", challenge):
            raise InvalidChallengeError("challenge contains non-hex characters")
        digest = Crypto.sha1_hmac_hash(self.config.private_key, challenge)
        return (self.config.public_key, digest) % "%s|%s"
dataset/ETHPy150Open braintree/braintree_python/braintree/webhook_notification_gateway.py/WebhookNotificationGateway.verify/swapped operands of `%`