}

    @Override
    public Iterable<? extends Character> successors(Character node) {
      requestedNodes.add(node);
      return delegate.successors(node);
    }
  }

  private static <N> SuccessorsFunction<N> fixedSuccessors(final Iterable<N> successors) {
    return new SuccessorsFunction<N>() {
      @Override
      public Iterable<N> successors(N n) {
        return successors;

   *     original iterable.
   * @throws NullPointerException if the specified iterable is null or has any null elements.
   * @since 12.0
   */
  public static <E extends Comparable<? super E>> Collection<List<E>> orderedPermutations(
      Iterable<E> elements) {
    return orderedPermutations(elements, Ordering.natural());
  }

  /**
   * Returns a {@link Collection} of all the permutations of the specified {@link Iterable} using

    } catch (UnsupportedOperationException expected) {
    }
  }

  /**
   * Verifies that an Iterator is unmodifiable.
   *
   * <p>This test only works with iterators that iterate over a finite set.
   */
  public static void assertIteratorIsUnmodifiable(Iterator<?> iterator) {
    while (iterator.hasNext()) {
      iterator.next();
      try {
        iterator.remove();

     * @since 19.0
     */
    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> putAll(Iterable<? extends Entry<? extends K, ? extends V>> entries) {
      super.putAll(entries);
      return this;
    }

    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> putAll(K key, Iterable<? extends V> values) {
      super.putAll(key, values);
      return this;
    }

     *
     * @param elements the {@code Iterable} to add to the {@code ImmutableMultiset}
     * @return this {@code Builder} object
     * @throws NullPointerException if {@code elements} is null or contains a null element
     */
    @CanIgnoreReturnValue
    @Override
    public Builder<E> addAll(Iterable<? extends E> elements) {
      if (elements instanceof Multiset) {

 *
 * <p>The collections returned by {@code keySet}, {@code keys}, and {@code asMap} iterate through
 * the keys in the order they were first added to the multimap. Similarly, {@code get}, {@code
 * removeAll}, and {@code replaceValues} return collections that iterate through the values in the
 * order they were added. The collections generated by {@code entries} and {@code values} iterate
 * across the key-value mappings in the order they were added to the multimap.
 *

      Comparator<? super E> comparator, Collection<? extends E> elements) {
    return copyOf(comparator, (Iterable<? extends E>) elements);
  }

  /**
   * Returns an immutable sorted set containing the elements of a sorted set, sorted by the same
   * {@code Comparator}. That behavior differs from {@link #copyOf(Iterable)}, which always uses the
   * natural ordering of the elements.
   *

  /** Returns an unmodifiable view of {@code iterable}. */
  public static <T extends @Nullable Object> Iterable<T> unmodifiableIterable(
      final Iterable<? extends T> iterable) {
    checkNotNull(iterable);
    if (iterable instanceof UnmodifiableIterable || iterable instanceof ImmutableCollection) {
      @SuppressWarnings("unchecked") // Since it's unmodifiable, the covariant cast is safe
      Iterable<T> result = (Iterable<T>) iterable;

  private static final Iterable<Integer> ITERABLE_ = Arrays.<Integer>asList();
  private static final Iterable<Integer> ITERABLE_1 = Arrays.asList(1);
  private static final Iterable<Integer> ITERABLE_12 = Arrays.asList(1, 2);
  private static final Iterable<Integer> ITERABLE_123 = Arrays.asList(1, 2, 3);
  private static final Iterable<@Nullable Integer> ITERABLE_NULL = Arrays.asList((Integer) null);

 * <p>The collections returned by {@link #keySet()} and {@link #asMap} iterate through the keys in
 * the order they were first added to the multimap. Similarly, {@link #get}, {@link #removeAll}, and
 * {@link #replaceValues} return collections that iterate through the values in the order they were
 * added. The collections generated by {@link #entries()}, {@link #keys()}, and {@link #values}