public void accept(@ParametricNullness T t) {
        this.holder = t;
      }

      @Override
      public boolean tryAdvance(Consumer<? super R> action) {
        if (fromSpliterator.tryAdvance(this)) {
          try {
            // The cast is safe because tryAdvance puts a T into `holder`.
            action.accept(function.apply(uncheckedCastNullableTToT(holder), index++));
            return true;

    }

    @Override
    void forEachRemaining(Consumer<? super E> action) {
      spliterator.forEachRemaining(action);
    }

    @Override
    boolean tryAdvance(Consumer<? super E> action) {
      return spliterator.tryAdvance(action);
    }

    @Override
    @Nullable GeneralSpliterator<E> trySplit() {
      Spliterator<E> split = spliterator.trySplit();

    }

    @Override
    void forEachRemaining(Consumer<? super E> action) {
      spliterator.forEachRemaining(action);
    }

    @Override
    boolean tryAdvance(Consumer<? super E> action) {
      return spliterator.tryAdvance(action);
    }

    @Override
    @Nullable GeneralSpliterator<E> trySplit() {
      Spliterator<E> split = spliterator.trySplit();

      public void accept(@ParametricNullness T t) {
        this.holder = t;
      }

      @Override
      public boolean tryAdvance(Consumer<? super R> action) {
        if (fromSpliterator.tryAdvance(this)) {
          try {
            // The cast is safe because tryAdvance puts a T into `holder`.
            action.accept(function.apply(uncheckedCastNullableTToT(holder), index++));
            return true;

    return new Spliterators.AbstractSpliterator<E>(
        size(), SPLITERATOR_CHARACTERISTICS | Spliterator.SIZED) {
      final UnmodifiableIterator<E> iterator = iterator();

      @Override
      public boolean tryAdvance(Consumer<? super E> action) {
        if (iterator.hasNext()) {
          action.accept(iterator.next());
          return true;
        } else {
          return false;
        }
      }