public static function add($btsHandle, $btsName, $pkg = false)
    {
        $app = Application::getFacadeApplication();
        $db = $app->make(Connection::class);
        $pkgID = (int) (is_object($pkg) ? $pkg->getPackageID() : $pkg);
        $displayOrder = $db->fetchColumn('select max(btsDisplayOrder) from BlockTypeSets');
        if ($displayOrder === null) {
            $displayOrder = 0;
        } else {
            ++$displayOrder;
        }
        $db->insert(
            'BlockTypeSets',
            [
                'btsHandle' => (string) $btsHandle,
                'btsName' => (string) $btsName,
                'pkgID' => $pkgID,
            ]
        );
        $id = $db->lastInsertId();

        $bs = static::getByID($id);

        return $bs;
    }