static NanoHTTPD.Response serveFile(File file) {
  ret serveFile(file, "application/octet-stream");
}

static NanoHTTPD.Response serveFile(File file, S mimeType) ctex {
  ret NanoHTTPD.newFixedLengthResponse(NanoHTTPD.Status.OK, mimeType, new FileInputStream(file), file.length());
}