sbool anyOverlap_intRanges(Collection<IntRange> c) {
  if (l(c) < 2) false;
  L<IntRange> l = sortedByField start(c);
  int x = first(l).end;
  for (int i = 1; i < l(l); i++) {
    IntRange r = l.get(i);
    if (r.start < x) true;
    x = r.end;
  }
  false;
}