static virtual NanoHTTPD.Response addFilenameHeader(virtual NanoHTTPD.Response r, S name) {
  call(r, "addHeader", "Content-Disposition", "inline; filename=\"" + name + "\""); // todo: encode special characters
  ret r;
}

static virtual NanoHTTPD.Response addFilenameHeader(S name, virtual NanoHTTPD.Response r) {
  ret addFilenameHeader(r, name);
}