}

  @LazyInit @CheckForNull private transient Set<Range<C>> asRanges;
  @LazyInit @CheckForNull private transient 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