for (E e : elements) {
      listIterator.add(e);
      changed = true;
    }
    return changed;
  }

  /** An implementation of {@link List#indexOf(Object)}. */
  static int indexOfImpl(List<?> list, @Nullable Object element) {
    if (list instanceof RandomAccess) {
      return indexOfRandomAccess(list, element);
    } else {
      ListIterator<?> listIterator = list.listIterator();

    for (E e : elements) {
      listIterator.add(e);
      changed = true;
    }
    return changed;
  }

  /** An implementation of {@link List#indexOf(Object)}. */
  static int indexOfImpl(List<?> list, @Nullable Object element) {
    if (list instanceof RandomAccess) {
      return indexOfRandomAccess(list, element);
    } else {
      ListIterator<?> listIterator = list.listIterator();

    int n = size();
    for (int i = 0; i < n; i++) {
      consumer.accept(get(i));
    }
  }

  @Override
  public int indexOf(@Nullable Object object) {
    return (object == null) ? -1 : Lists.indexOfImpl(this, object);
  }

  @Override
  public int lastIndexOf(@Nullable Object object) {
    return (object == null) ? -1 : Lists.lastIndexOfImpl(this, object);
  }

  @Override