def get_response(self, key, serializable=False):
        """Get the value of a key from etcd."""
        range_request = self._build_get_range_request(
            key,
            serializable=serializable
        )

        return self.kvstub.Range(
            range_request,
            self.timeout,
            credentials=self.call_credentials,
            metadata=self.metadata
        )
Get the value of a key from etcd.