// step = e.g. 100
// value = 0 to count
static S pageNav2(S baseLink, int count, int value, int step, S nVar, O... _) {
  new L<S> l;
  baseLink = unnull(baseLink) + (contains(baseLink, "?") ? "&" : "?") + urlencode(nVar) + "=";
  if (value > 0) l.add(ahref(baseLink + max(0, value-step),
    stringPar leftArrow(_, htmlencode(unicode_leftPointingTriangle()))));
  for (int i = 0; i < count; i += step) {
    int n = i/step+1;
    if (pageNav2_showPage(value, i, step, count))
      if (value == i)
        l.add(b(n));
      else
        l.add(ahref(baseLink + i, n));
  }
  if (value+step < count) l.add(ahref(baseLink + (value+step),
    stringPar rightArrow(_, htmlencode(unicode_rightPointingTriangle()))));
  ret p("Pages: " + lines(l));
}

sbool pageNav2_showPage(int actual, int i, int step, int count) {
  int diff = abs(actual-i)/step;
  ret i == 0
    || i >= (count-1)/step*step
    || diff <= 10
    || diff <= 100 && ((i/step) % 10) == 9
    || diff <= 1000 && ((i/step) % 100) == 99
    || ((i/step) % 1000) == 999;
}