}

  /**
   * Removes a number of occurrences of the specified element from this multiset. If the multiset
   * contains fewer than this number of occurrences to begin with, all occurrences will be removed.
   *
   * @param element the element whose occurrences should be removed
   * @param occurrences the number of occurrences of the element to remove
   * @return the count of the element before the operation; possibly zero

      return 0;
    }

    @Override
    public int add(E element, int occurrences) {
      checkArgument(occurrences >= 0);
      Integer frequency = backingMap.get(element);
      if (frequency == null) {
        frequency = 0;
      }
      if (occurrences == 0) {
        return frequency;
      }
      checkArgument(occurrences <= Integer.MAX_VALUE - frequency);
      backingMap.put(element, frequency + occurrences);

   *     Integer#MAX_VALUE} occurrences of {@code element} in this multiset.
   */
  @CanIgnoreReturnValue
  @Override
  public int add(@ParametricNullness E element, int occurrences) {
    if (occurrences == 0) {
      return count(element);
    }
    checkArgument(occurrences > 0, "occurrences cannot be negative: %s", occurrences);
    Count frequency = backingMap.get(element);
    int oldCount;

      checkArgument(
          predicate.apply(element), "Element %s does not match predicate %s", element, predicate);
      return unfiltered.add(element, occurrences);
    }

    @Override
    public int remove(@CheckForNull Object element, int occurrences) {
      checkNonnegative(occurrences, "occurrences");
      if (occurrences == 0) {
        return count(element);

      checkArgument(
          predicate.apply(element), "Element %s does not match predicate %s", element, predicate);
      return unfiltered.add(element, occurrences);
    }

    @Override
    public int remove(@CheckForNull Object element, int occurrences) {
      checkNonnegative(occurrences, "occurrences");
      if (occurrences == 0) {
        return count(element);

      return 0;
    }

    @Override
    public int add(E element, int occurrences) {
      checkArgument(occurrences >= 0);
      Integer frequency = backingMap.get(element);
      if (frequency == null) {
        frequency = 0;
      }
      if (occurrences == 0) {
        return frequency;
      }
      checkArgument(occurrences <= Integer.MAX_VALUE - frequency);
      backingMap.put(element, frequency + occurrences);

  class Keys extends Multimaps.Keys<K, V> {
    Keys() {
      super(FilteredEntryMultimap.this);
    }

    @Override
    public int remove(@CheckForNull Object key, int occurrences) {
      checkNonnegative(occurrences, "occurrences");
      if (occurrences == 0) {
        return count(key);
      }
      Collection<V> collection = unfiltered.asMap().get(key);
      if (collection == null) {
        return 0;
      }

  class Keys extends Multimaps.Keys<K, V> {
    Keys() {
      super(FilteredEntryMultimap.this);
    }

    @Override
    public int remove(@CheckForNull Object key, int occurrences) {
      checkNonnegative(occurrences, "occurrences");
      if (occurrences == 0) {
        return count(key);
      }
      Collection<V> collection = unfiltered.asMap().get(key);
      if (collection == null) {
        return 0;
      }

      return 0;
    }
  }

  @CanIgnoreReturnValue
  @Override
  public int add(@ParametricNullness E element, int occurrences) {
    checkNonnegative(occurrences, "occurrences");
    if (occurrences == 0) {
      return count(element);
    }
    checkArgument(range.contains(element));
    AvlNode<E> root = rootReference.get();
    if (root == null) {

     * @throws IllegalArgumentException if {@code occurrences} is negative, or if this operation
     *     would result in more than {@link Integer#MAX_VALUE} occurrences of the element
     */
    @CanIgnoreReturnValue
    @Override
    public Builder<E> addCopies(E element, int occurrences) {
      checkNotNull(element);
      CollectPreconditions.checkNonnegative(occurrences, "occurrences");
      if (occurrences == 0) {