@SuppressWarnings({"serial", "rawtypes"})
@ElementTypesAreNonnullByDefault
final class RegularImmutableSortedSet<E> extends ImmutableSortedSet<E> {
  static final RegularImmutableSortedSet<Comparable> NATURAL_EMPTY_SET =
      new RegularImmutableSortedSet<>(ImmutableList.<Comparable>of(), Ordering.natural());

  private final transient ImmutableList<E> elements;

  RegularImmutableSortedSet(ImmutableList<E> elements, Comparator<? super E> comparator) {

  static final ImmutableSortedMultiset<?> NATURAL_EMPTY_MULTISET =
      new RegularImmutableSortedMultiset<>(Ordering.natural());

  @VisibleForTesting final transient RegularImmutableSortedSet<E> elementSet;
  private final transient long[] cumulativeCounts;
  private final transient int offset;
  private final transient int length;

  RegularImmutableSortedMultiset(Comparator<? super E> comparator) {

   */
  @Override
  ImmutableList<E> subListUnchecked(int fromIndex, int toIndex) {
    ImmutableList<E> parentSubList = super.subListUnchecked(fromIndex, toIndex);
    return new RegularImmutableSortedSet<E>(parentSubList, comparator()).asList();
  }

  @Override
  public Spliterator<E> spliterator() {
    return CollectSpliterators.indexed(
        size(),