// params = relative link, HTML, relative link, HTML, ...
static S hBoolSelector(bool value, S... params) {
  new L<S> l;
  for (int i = 0; i < l(params); i += 2) {
    bool selected = value != (i == 0);
    S link = params[i], html = params[i+1];
    if (selected)
      l.add(b("[" + html + "]"));
    else
      l.add(ahref(rawSelfLink(link), html));
  }
  ret join(" | ", l);
}