this.rangesByLowerBound = rangesByLowerCut;
  }

  @LazyInit private transient @Nullable Set<Range<C>> asRanges;
  @LazyInit private transient @Nullable Set<Range<C>> asDescendingSetOfRanges;

  @Override
  public Set<Range<C>> asRanges() {
    Set<Range<C>> result = asRanges;
    return (result == null) ? asRanges = new AsRanges(rangesByLowerBound.values()) : result;
  }

  @Override
  public Set<Range<C>> asDescendingSetOfRanges() {

   * returns an {@code ImmutableRangeSet}.
   *
   * @since 21.0
   */
  public ImmutableRangeSet<C> union(RangeSet<C> other) {
    return unionOf(Iterables.concat(asRanges(), other.asRanges()));
  }

  /**
   * Returns a new range set consisting of the intersection of this range set and {@code other}.
   *
   * <p>This is essentially the same as {@code