}

  @Override
  public Map<Range<K>, V> asMapOfRanges() {
    return new AsMapOfRanges(entriesByLowerBound.values());
  }

  @Override
  public Map<Range<K>, V> asDescendingMapOfRanges() {
    return new AsMapOfRanges(entriesByLowerBound.descendingMap().values());
  }

  private final class AsMapOfRanges extends IteratorBasedAbstractMap<Range<K>, V> {

        new RegularImmutableSortedSet<>(ranges, Range.<K>rangeLexOrdering());
    return new ImmutableSortedMap<>(rangeSet, values);
  }

  @Override
  public ImmutableMap<Range<K>, V> asDescendingMapOfRanges() {
    if (ranges.isEmpty()) {
      return ImmutableMap.of();
    }
    RegularImmutableSortedSet<Range<K>> rangeSet =

        new RegularImmutableSortedSet<>(ranges, Range.<K>rangeLexOrdering());
    return new ImmutableSortedMap<>(rangeSet, values);
  }

  @Override
  public ImmutableMap<Range<K>, V> asDescendingMapOfRanges() {
    if (ranges.isEmpty()) {
      return ImmutableMap.of();
    }
    RegularImmutableSortedSet<Range<K>> rangeSet =