return ImmutableSet.of();
    }
    return new RegularImmutableSortedSet<>(ranges, Range.rangeLexOrdering());
  }

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

  private static final class ComplementRanges<C extends Comparable>