protected function runLongOperation($op, $method = 'post', array $body = [])
    {
        $result = $this->runOperation($op, $method, $body);
        $activities = $result->getActivities();
        if (count($activities) !== 1) {
            trigger_error(sprintf("Expected one activity, found %d", count($activities)), E_USER_WARNING);
        }

        return reset($activities);
    }