E e = (E) element;
        return predicate.apply(e);
      }
      return false;
    }

    @Override
    public boolean containsAll(Collection<?> collection) {
      return containsAllImpl(this, collection);
    }

    @Override
    public boolean isEmpty() {
      return !Iterables.any(unfiltered, predicate);
    }

    @Override
    public Iterator<E> iterator() {