public static function send($file, $display_file_name = '', $seekat=0)
    {
        $display_file_name = $display_file_name ? $display_file_name : basename($file);
        $display_file_name = str_replace(" ", "_", $display_file_name);
        header("HTTP/1.1 200 OK");
        header("Status: 200 OK");
        header("Pragma: private");
        header("Expires: 0");
        header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
        header("Content-Transfer-Encoding: Binary");
        header('Content-Type: application/force-download');
        header('Content-disposition: attachment; filename="'.$display_file_name.'"');

        while (ob_get_level() > 0) {
            ob_end_flush();
        }
        \sb\Files::readChunked($file, $seekat);
    }