public function trimFilename(string $prefix): bool
    {
        $affected = false;
        $len = strlen($prefix);
        foreach ($this->props['items'] as &$item) {
            if ((!empty($item['file'])) && (strpos($item['file'], $prefix) === 0)) {
                $item['file'] = substr($item['file'], $len);
                $affected = true;
            }
        }
        unset($item);
        return $affected;
    }