return CollectSpliterators.filter(unfiltered.spliterator(), predicate);
    }

    @Override
    public void forEach(Consumer<? super E> action) {
      checkNotNull(action);
      unfiltered.forEach(
          (E e) -> {
            if (predicate.test(e)) {
              action.accept(e);
            }
          });
    }

    @Override
    public boolean remove(@CheckForNull Object element) {