*
   * @since 3.0
   */
  public static <E extends @Nullable Object> SetView<E> symmetricDifference(
      final Set<? extends E> set1, final Set<? extends E> set2) {
    checkNotNull(set1, "set1");
    checkNotNull(set2, "set2");

    return new SetView<E>() {
      @Override
      public UnmodifiableIterator<E> iterator() {
        final Iterator<? extends E> itr1 = set1.iterator();

    return checkNotNull(multiset);
  }

  static class UnmodifiableMultiset<E extends @Nullable Object> extends ForwardingMultiset<E>
      implements Serializable {
    final Multiset<? extends E> delegate;

    UnmodifiableMultiset(Multiset<? extends E> delegate) {
      this.delegate = delegate;
    }

    @SuppressWarnings("unchecked")
    @Override

      Iterable<? extends Entry<? extends K, ? extends V>> entries) {
    return new Builder<K, V>().putAll(entries).build();
  }

  /** Creates an ImmutableSetMultimap from an asMap.entrySet. */
  static <K, V> ImmutableSetMultimap<K, V> fromMapEntries(
      Collection<? extends Map.Entry<? extends K, ? extends Collection<? extends V>>> mapEntries,

      return copyOf(table.cellSet());
    }
  }

  static <R, C, V> ImmutableTable<R, C, V> copyOf(
      Iterable<? extends Cell<? extends R, ? extends C, ? extends V>> cells) {
    ImmutableTable.Builder<R, C, V> builder = ImmutableTable.builder();
    for (Cell<? extends R, ? extends C, ? extends V> cell : cells) {
      builder.put(cell);
    }
    return builder.build();
  }

  /**

  @Beta // TODO: b/288085449 - Remove.
  public static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableSortedMap<K, V>> toImmutableSortedMap(
          Comparator<? super K> comparator,
          Function<? super T, ? extends K> keyFunction,
          Function<? super T, ? extends V> valueFunction) {
    return CollectCollectors.toImmutableSortedMap(comparator, keyFunction, valueFunction);

   * always true when the iterable has fewer than two elements.
   */
  public static <T extends @Nullable Object> boolean isInOrder(
      Iterable<? extends T> iterable, Comparator<T> comparator) {
    checkNotNull(comparator);
    Iterator<? extends T> it = iterable.iterator();
    if (it.hasNext()) {
      T prev = it.next();
      while (it.hasNext()) {
        T next = it.next();

  @Beta // TODO: b/288085449 - Remove.
  public static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableBiMap<K, V>> toImmutableBiMap(
          Function<? super T, ? extends K> keyFunction,
          Function<? super T, ? extends V> valueFunction) {
    return CollectCollectors.toImmutableBiMap(keyFunction, valueFunction);
  }

  /**

     * operation O(1).
     */

    @CheckForNull private Iterator<? extends Iterator<? extends T>> topMetaIterator;

    // Only becomes nonnull if we encounter nested concatenations.
    @CheckForNull private Deque<Iterator<? extends Iterator<? extends T>>> metaIterators;

    ConcatenatedIterator(Iterator<? extends Iterator<? extends T>> metaIterator) {
      iterator = emptyIterator();

  @Beta // TODO: b/288085449 - Remove.
  public static <T extends @Nullable Object, K extends Comparable<? super K>, V>
      Collector<T, ?, ImmutableRangeMap<K, V>> toImmutableRangeMap(
          Function<? super T, Range<K>> keyFunction,
          Function<? super T, ? extends V> valueFunction) {
    return CollectCollectors.toImmutableRangeMap(keyFunction, valueFunction);
  }

  /**

  public static <
          T extends @Nullable Object,
          K extends @Nullable Object,
          V extends @Nullable Object,
          M extends Multimap<K, V>>
      Collector<T, ?, M> flatteningToMultimap(
          java.util.function.Function<? super T, ? extends K> keyFunction,
          java.util.function.Function<? super T, ? extends Stream<? extends V>> valueFunction,