protected function mergeMethods($nodeData)/*# : array */
    {
        // no merge
        if (empty($nodeData) || isset($nodeData[0])) {
            return (array) $nodeData;
        }

        // in sections
        $result = [];
        foreach ($nodeData as $data) {
            $result = array_merge($result, $data);
        }
        return $result;
    }