def register_cipher_adapter(self, cipher_cls, mode_cls, adapter):
        if self._cipher_registry in (cipher_cls, mode_cls):
            raise ValueError("Duplicate registration for: {0} {1}.".format(
                cipher_cls, mode_cls)
            )
        self._cipher_registry[cipher_cls, mode_cls] = adapter
dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/cryptography-1.3.1/src/cryptography/hazmat/backends/openssl/backend.py/Backend.register_cipher_adapter/swapped operands of `in`