this.range = GeneralRange.all(comparator);
    this.header = new AvlNode<>();
    successor(header, header);
    this.rootReference = new Reference<>();
  }

  /** A function which can be summed across a subtree. */
  private enum Aggregate {
    SIZE {
      @Override
      int nodeAggregate(AvlNode<?> node) {
        return node.elemCount;
      }

      @Override

   * being a real directory to being a symlink to another directory. It then calls
   * deleteDirectoryContents thousands of times on a directory whose subtree contains the file
   * that's switching between directory and symlink to try to ensure that under no circumstance does
   * deleteDirectoryContents follow the symlink to the other directory and delete that directory's

   *   <li>Nulls test is not performed on method return values unless the method is a non-private
   *       static factory method whose return type is {@code cls} or {@code cls}'s subtype.
   * </ul>
   */
  public void testNulls(Class<?> cls) {
    try {
      doTestNulls(cls, Visibility.PACKAGE);
    } catch (Exception e) {
      throwIfUnchecked(e);
      throw new RuntimeException(e);

 *   <li>graphs that do/don't allow self-loops
 *   <li>graphs whose nodes/edges are insertion-ordered, sorted, or unordered
 *   <li>graphs whose edges have associated values
 * </ul>
 *
 * <p>{@code ValueGraph}, as a subtype of {@code Graph}, explicitly does not support parallel edges,
 * and forbids implementations or extensions with parallel edges. If you need parallel edges, use

   * @throws NullPointerException if any of {@code elements} is null
   */
  public static <E> ImmutableSortedSet<E> copyOf(Iterable<? extends E> elements) {
    // Hack around E not being a subtype of Comparable.
    // Unsafe, see ImmutableSortedSetFauxverideShim.
    @SuppressWarnings("unchecked")
    Ordering<E> naturalOrder = (Ordering<E>) Ordering.<Comparable<?>>natural();
    return copyOf(naturalOrder, elements);

   * @throws NullPointerException if any of {@code elements} is null
   */
  public static <E> ImmutableSortedSet<E> copyOf(Iterable<? extends E> elements) {
    // Hack around E not being a subtype of Comparable.
    // Unsafe, see ImmutableSortedSetFauxverideShim.
    @SuppressWarnings("unchecked")
    Ordering<E> naturalOrder = (Ordering<E>) Ordering.<Comparable<?>>natural();
    return copyOf(naturalOrder, elements);

      void visitClass(Class<?> t) {
        result.set(t.getComponentType());
      }
    }.visit(type);
    return result.get();
  }

  /**
   * Returns {@code ? extends X} if any of {@code bounds} is a subtype of {@code X[]}; or null
   * otherwise.
   */
  @CheckForNull
  private static Type subtypeOfComponentType(Type[] bounds) {
    for (Type bound : bounds) {
      Type componentType = getComponentType(bound);

   * includes exceptional exits, so all control paths involving signalling must be protected by a
   * finally block.
   *
   * Further optimizations of this algorithm become increasingly subtle. A wait that terminates
   * without the guard being satisfied (due to timeout, but not interrupt) can then immediately exit
   * the monitor without signalling. If it timed out without being signalled, it does not need to

    return new InstanceOfPredicate<>(clazz);
  }

  /**
   * Returns a predicate that evaluates to {@code true} if the class being tested is assignable to
   * (is a subtype of) {@code clazz}. Example:
   *
   * <pre>{@code
   * List<Class<?>> classes = Arrays.asList(
   *     Object.class, String.class, Number.class, Long.class);

   * @throws NullPointerException if any of {@code elements} is null
   */
  public static <E> ImmutableSortedMultiset<E> copyOf(Iterable<? extends E> elements) {
    // Hack around E not being a subtype of Comparable.
    // Unsafe, see ImmutableSortedMultisetFauxverideShim.
    @SuppressWarnings("unchecked")
    Ordering<E> naturalOrder = (Ordering<E>) Ordering.<Comparable<?>>natural();