* Implementation of {@link Multimaps#filterKeys(ListMultimap, Predicate)}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
final class FilteredKeyListMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends FilteredKeyMultimap<K, V> implements ListMultimap<K, V> {
  FilteredKeyListMultimap(ListMultimap<K, V> unfiltered, Predicate<? super K> keyPredicate) {
    super(unfiltered, keyPredicate);
  }

  @Override

    if (unfiltered instanceof FilteredKeyListMultimap) {
      FilteredKeyListMultimap<K, V> prev = (FilteredKeyListMultimap<K, V>) unfiltered;
      return new FilteredKeyListMultimap<>(
          prev.unfiltered(), Predicates.and(prev.keyPredicate, keyPredicate));
    } else {
      return new FilteredKeyListMultimap<>(unfiltered, keyPredicate);
    }
  }

  /**