private function handleResponse($response)
    {
        if ($response instanceof PagedListResponse || $response instanceof GaxPagedListResponse) {
            $response = $response->getPage()->getResponseObject();
        }

        if ($response instanceof Message) {
            return $this->serializer->encodeMessage($response);
        }

        if ($response instanceof OperationResponse || $response instanceof GaxOperationResponse) {
            return $response;
        }

        if ($response instanceof ServerStream || $response instanceof GaxServerStream) {
            return $this->handleStream($response);
        }

        return null;
    }