Fetch the data for the model from Redis and assign the values.

        :rtype: bool

def fetch(self):
        """Fetch the data for the model from Redis and assign the values.

        :rtype: bool

        """
        raw = yield gen.Task(self._redis_client.get, self._key)
        if raw:
            self.loads(base64.b64decode(raw))
            raise gen.Return(True)
        raise gen.Return(False)