}

  Set<Cell<R, C, V>> createCellSet() {
    return new CellSet();
  }

  abstract Iterator<Table.Cell<R, C, V>> cellIterator();

  abstract Spliterator<Table.Cell<R, C, V>> cellSpliterator();

  @WeakOuter
  private final class CellSet extends AbstractSet<Cell<R, C, V>> {
    @Override
    public boolean contains(@Nullable Object o) {
      if (o instanceof Cell) {

      @Override
      protected Cell<R, C, @Nullable V> get(int index) {
        return getCell(index);
      }
    };
  }

  @Override
  Spliterator<Cell<R, C, @Nullable V>> cellSpliterator() {
    return CollectSpliterators.<Cell<R, C, @Nullable V>>indexed(
        size(), Spliterator.ORDERED | Spliterator.NONNULL | Spliterator.DISTINCT, this::getCell);
  }

       */
      if (requireNonNull(rowEntry).getValue().isEmpty()) {
        rowIterator.remove();
        rowEntry = null;
      }
    }
  }

  @Override
  Spliterator<Cell<R, C, V>> cellSpliterator() {
    return CollectSpliterators.flatMap(
        backingMap.entrySet().spliterator(),
        (Entry<R, Map<C, V>> rowEntry) ->
            CollectSpliterators.map(