return (result == null) ? cellSet = createCellSet() : result;
  }

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

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

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

    return (result == null) ? cellSet = createCellSet() : result;
  }

  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
  class CellSet extends AbstractSet<Cell<R, C, V>> {
    @Override
    public boolean contains(@CheckForNull Object o) {