protected static function _processFolders($secureFolders)
    {
        $secureFolders = array_filter(is_array($secureFolders) ? $secureFolders : explode(',', $secureFolders), 'trim');
        foreach ($secureFolders as $k => $folder) {
            $secureFolders[$k] = '/' . trim($folder, '/');
        }
        if (in_array('/', $secureFolders)) {
            return ['/']; // all uploads are secure
        }
        foreach ($secureFolders as $k => $folder) {
            foreach ($secureFolders as $folderCheck) {
                if (strpos($folder, $folderCheck . '/') === 0) {
                    unset($secureFolders[$k]);
                }
            }
        }
        return $secureFolders;
    }