};
  }

  /**
   * Returns the element at the specified position in an iterable.
   *
   * <p><b>{@code Stream} equivalent:</b> {@code stream.skip(position).findFirst().get()} (throws
   * {@code NoSuchElementException} if out of bounds)
   *
   * @param position position of the element to return
   * @return the element at the specified position in {@code iterable}

  abstract ImmutableSortedSet<E> createDescendingSet();

  /** @since 12.0 */
  @GwtIncompatible // NavigableSet
  @Override
  public abstract UnmodifiableIterator<E> descendingIterator();

  /** Returns the position of an element within the set, or -1 if not present. */
  abstract int indexOf(@CheckForNull Object target);

  /*
   * This class is used to serialize all ImmutableSortedSet instances,

   * {@code k} is the size of the returned {@code ImmutableSet}, then the unique elements of {@code
   * elements} will be in the first {@code k} positions, and {@code elements[i] == null} for {@code
   * k <= i < n}.
   *
   * <p>After this method returns, {@code elements} will contain no duplicates, but {@code elements}

     */

    private final Comparator<? super E> comparator;

    @VisibleForTesting E[] elements;
    private int[] counts;

    /*
     * The number of used positions in the elements array.  We deduplicate periodically, so this
     * may fluctuate up and down.
     */
    private int length;