code: private static <T extends Comparable<T>> Optional<Range<T>> smallestContainerForRange(
        Collection<Range<T>> ranges, Range<T> target) {
      Range<T> best = Range.all();
      for (final Range<T> r : ranges) {
        if (r.equals(target)) {
          continue;
        }
        // prefer a smaller range, always;
        if (r.encloses(target) && best.encloses(r)) {
          best = r;
        }
      }
      if (best.equals(Range.<T>all())) {
        return Optional.absent();
      }
      return Optional.of(best);
    }
docs: Assuming our ranges look tree-structured, finds the "smallest" range for the particular target
  one.