}

  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) {