}

  /** 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();
      while (listIterator.hasNext()) {
        if (Objects.equals(element, listIterator.next())) {