protected function isGuzzleException(Exception $e)
    {
        return (    is_a($e, GuzzleException\BadResponseException::class)
                ||  is_a($e, GuzzleException\ClientException::class)
                ||  is_a($e, GuzzleException\ConnectException::class)
                ||  is_a($e, GuzzleException\RequestException::class)
                ||  is_a($e, GuzzleException\SeekException::class)
                ||  is_a($e, GuzzleException\ServerException::class)
                ||  is_a($e, GuzzleException\TooManyRedirectsException::class)
                ||  is_a($e, GuzzleException\TransferException::class)
        );
    }