private function buildVersion(SimpleXMLElement $version): array
    {
        $apis = [];
        $guides = [];
        foreach ($version->children() as $child) {
            switch ($child->getName()) {
                case 'api':
                    $apis[] = $this->buildApi($child);
                    break;
                case 'guide':
                    $guides[] = $this->buildGuide($child);
                    break;
                default:
                    break;
            }
        }

        $version = [
            'folder' => (string) $version->folder,
        ];

        if (count($apis) > 0) {
            $version['api'] = $apis;
        }

        if (count($guides) > 0) {
            $version['guide'] = $guides;
        }

        return $version;
    }