class DownloadTool {
    public static File download(String urlString) throws IOException {<FILL_FUNCTION_BODY>}
}

        URL url = new URL(urlString);
        URLConnection con = url.openConnection();
        InputStream is = con.getInputStream();
        byte[] bs = new byte[1024];
        int len;

        long time = Calendar.getInstance().getTimeInMillis();
        String tail = "";
        if (urlString.lastIndexOf(".") != -1) {
            tail = urlString.substring(urlString.lastIndexOf(".") + 1);
        }
        String filename = "test-output" + File.separator + "download-" + time + "." + tail;
        File file = new File(filename);
        FileOutputStream os;
        os = new FileOutputStream(file, true);
        while ((len = is.read(bs)) != -1) {
            os.write(bs, 0, len);
        }
        os.close();
        is.close();
        return file;
    
<no_super_class>