@classmethod
    def lookup(cls, name):
        """Look up the signature key type.

        :param name: the name of the signature key type
        :returns: the SignatureKeyType object
        :raises: SignatureVerificationError if signature key type is invalid
        """
        if name not in cls._REGISTERED_TYPES:
            raise exception.SignatureVerificationError(
                reason=_('Invalid signature key type: %s') + name)
        return cls._REGISTERED_TYPES[name]


# each key type will require its own verifier
dataset/ETHPy150Open BU-NU-CLOUD-SP16/Trusted-Platform-Module-nova/nova/signature_utils.py/SignatureKeyType.lookup/operator `%` -> `+`