}

    @Override
    public boolean removeAll(final Collection<?> collection) {
      return removeIf(collection::contains);
    }

    @Override
    public boolean retainAll(final Collection<?> collection) {
      return removeIf(element -> !collection.contains(element));
    }

    @Override

    StringBuilder sb = newStringBuilderForCollection(collection.size()).append('[');
    boolean first = true;
    for (Object o : collection) {
      if (!first) {
        sb.append(", ");
      }
      first = false;
      if (o == collection) {
        sb.append("(this Collection)");
      } else {
        sb.append(o);
      }
    }
    return sb.append(']').toString();

    return Collections.unmodifiableCollection(collection);
  }

  @Override
  public void clear() {
    // Clear each collection, to make previously returned collections empty.
    for (Collection<V> collection : map.values()) {
      collection.clear();
    }
    map.clear();
    totalSize = 0;
  }

  // Views

  /**
   * {@inheritDoc}
   *

   */
  public static boolean elementsEqual(Iterable<?> iterable1, Iterable<?> iterable2) {
    if (iterable1 instanceof Collection && iterable2 instanceof Collection) {
      Collection<?> collection1 = (Collection<?>) iterable1;
      Collection<?> collection2 = (Collection<?>) iterable2;
      if (collection1.size() != collection2.size()) {
        return false;
      }
    }

   * </ol>
   *
   * @param collection the presumed-immutable collection
   * @param sampleElement an element of the same type as that contained by {@code collection}.
   *     {@code collection} may or may not have {@code sampleElement} as a member.
   */
  public static <E extends @Nullable Object> void assertCollectionIsUnmodifiable(
      Collection<E> collection, E sampleElement) {
    Collection<E> siblingCollection = new ArrayList<>();

   */
  Collection<V> values();

  /**
   * Returns a view collection of all key-value pairs contained in this multimap, as {@link Entry}
   * instances.
   *
   * <p>Changes to the returned collection or the entries it contains will update the underlying
   * multimap, and vice versa. However, <i>adding</i> to the returned collection is not possible.
   */

    while (entryIterator.hasNext()) {
      Entry<K, Collection<V>> entry = entryIterator.next();
      K key = entry.getKey();
      Collection<V> collection = filterCollection(entry.getValue(), new ValuePredicate(key));
      if (!collection.isEmpty()
          && predicate.apply(Maps.<K, Collection<V>>immutableEntry(key, collection))) {
        if (collection.size() == entry.getValue().size()) {
          entryIterator.remove();
        } else {

    assertPermutationsCount(1, Collections2.permutations(Collections.<Integer>emptyList()));
    assertPermutationsCount(1, Collections2.permutations(newArrayList(1)));
    assertPermutationsCount(2, Collections2.permutations(newArrayList(1, 2)));
    assertPermutationsCount(6, Collections2.permutations(newArrayList(1, 2, 3)));
    assertPermutationsCount(5040, Collections2.permutations(newArrayList(1, 2, 3, 4, 5, 6, 7)));

    assertPermutationsCount(1, Collections2.permutations(Collections.<Integer>emptyList()));
    assertPermutationsCount(1, Collections2.permutations(newArrayList(1)));
    assertPermutationsCount(2, Collections2.permutations(newArrayList(1, 2)));
    assertPermutationsCount(6, Collections2.permutations(newArrayList(1, 2, 3)));
    assertPermutationsCount(5040, Collections2.permutations(newArrayList(1, 2, 3, 4, 5, 6, 7)));

  private static final Feature<?>[] COLLECTION_FEATURES = {
    CollectionSize.ANY, CollectionFeature.ALLOWS_NULL_QUERIES
  };

  private static final Feature<?>[] COLLECTION_FEATURES_ORDER = {
    CollectionSize.ANY, CollectionFeature.KNOWN_ORDER, CollectionFeature.ALLOWS_NULL_QUERIES
  };

  private static final Feature<?>[] COLLECTION_FEATURES_REMOVE = {