}

  /** Remove each element in an iterable from a set. */
  static boolean removeAllImpl(Set<?> set, Iterator<?> iterator) {
    boolean changed = false;
    while (iterator.hasNext()) {
      changed |= set.remove(iterator.next());
    }
    return changed;
  }

  static boolean removeAllImpl(Set<?> set, Collection<?> collection) {
    checkNotNull(collection); // for GWT

  }

  /** Remove each element in an iterable from a set. */
  static boolean removeAllImpl(Set<?> set, Iterator<?> iterator) {
    boolean changed = false;
    while (iterator.hasNext()) {
      changed |= set.remove(iterator.next());
    }
    return changed;
  }

  static boolean removeAllImpl(Set<?> set, Collection<?> collection) {
    checkNotNull(collection); // for GWT

    if (elements.isEmpty()) {
      return false;
    }
    elements.addTo(self);
    return true;
  }

  /** An implementation of {@link Multiset#removeAll}. */
  static boolean removeAllImpl(Multiset<?> self, Collection<?> elementsToRemove) {
    Collection<?> collection =
        (elementsToRemove instanceof Multiset)
            ? ((Multiset<?>) elementsToRemove).elementSet()
            : elementsToRemove;

    if (elements.isEmpty()) {
      return false;
    }
    elements.forEachEntry(self::add);
    return true;
  }

  /** An implementation of {@link Multiset#removeAll}. */
  static boolean removeAllImpl(Multiset<?> self, Collection<?> elementsToRemove) {
    Collection<?> collection =
        (elementsToRemove instanceof Multiset)
            ? ((Multiset<?>) elementsToRemove).elementSet()
            : elementsToRemove;

   *
   * @since 7.0 (this version overrides the {@code ForwardingCollection} version as of 12.0)
   */
  @Override
  protected boolean standardRemoveAll(Collection<?> collection) {
    return Sets.removeAllImpl(this, checkNotNull(collection)); // for GWT
  }

  /**
   * A sensible definition of {@link #equals} in terms of {@link #size} and {@link #containsAll}. If

   *
   * @since 7.0 (this version overrides the {@code ForwardingCollection} version as of 12.0)
   */
  @Override
  protected boolean standardRemoveAll(Collection<?> collection) {
    return Sets.removeAllImpl(this, checkNotNull(collection)); // for GWT
  }

  /**
   * A sensible definition of {@link #equals} in terms of {@link #size} and {@link #containsAll}. If

    return Multisets.addAllImpl(this, elementsToAdd);
  }

  @CanIgnoreReturnValue
  @Override
  public final boolean removeAll(Collection<?> elementsToRemove) {
    return Multisets.removeAllImpl(this, elementsToRemove);
  }

  @CanIgnoreReturnValue
  @Override
  public final boolean retainAll(Collection<?> elementsToRetain) {
    return Multisets.retainAllImpl(this, elementsToRetain);
  }

    return Multisets.addAllImpl(this, elementsToAdd);
  }

  @CanIgnoreReturnValue
  @Override
  public final boolean removeAll(Collection<?> elementsToRemove) {
    return Multisets.removeAllImpl(this, elementsToRemove);
  }

  @CanIgnoreReturnValue
  @Override
  public final boolean retainAll(Collection<?> elementsToRetain) {
    return Multisets.retainAllImpl(this, elementsToRetain);
  }

        /*
         * We can't inherit the normal implementation (which calls
         * Sets.removeAllImpl(Set, *Collection*)) because, under some
         * circumstances, it attempts to call columnKeySet().iterator().remove,
         * which is unsupported.
         */
        checkNotNull(c);
        return Sets.removeAllImpl(this, c.iterator());
      }

      @Override
      public boolean retainAll(Collection<?> c) {

   * to forward to this implementation.
   *
   * @since 7.0
   */
  @Override
  protected boolean standardRemoveAll(Collection<?> elementsToRemove) {
    return Multisets.removeAllImpl(this, elementsToRemove);
  }

  /**
   * A sensible definition of {@link #retainAll} in terms of the {@code retainAll} method of {@link