if (ranges.isEmpty()) {
      return ImmutableSet.of();
    }
    return new RegularImmutableSortedSet<>(ranges.reverse(), Range.<C>rangeLexOrdering().reverse());
  }

  private static final class ComplementRanges<C extends Comparable>
      extends ImmutableList<Range<C>> {

    private final ImmutableList<Range<C>> ranges;

    // True if the "positive" range set is empty or bounded below.