public int indexOf(@Nullable Object object) {
      int index = forwardList.lastIndexOf(object);
      return (index >= 0) ? reverseIndex(index) : -1;
    }

    @Override
    public int lastIndexOf(@Nullable Object object) {
      int index = forwardList.indexOf(object);
      return (index >= 0) ? reverseIndex(index) : -1;
    }

    @Override
    public ImmutableList<E> subList(int fromIndex, int toIndex) {