@Override
  final ImmutableSet<Cell<R, C, V>> createCellSet() {
    return isEmpty() ? ImmutableSet.<Cell<R, C, V>>of() : new CellSet();
  }

  @WeakOuter
  private final class CellSet extends IndexedImmutableSet<Cell<R, C, V>> {
    @Override
    public int size() {
      return RegularImmutableTable.this.size();
    }

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

  }

  @Override
  ImmutableSet<K> createKeySet() {
    return new KeySet<>(this);
  }

  @GwtCompatible(emulated = true)
  private static final class KeySet<K> extends IndexedImmutableSet<K> {
    private final RegularImmutableMap<K, ?> map;

    KeySet(RegularImmutableMap<K, ?> map) {
      this.map = map;
    }

    @Override
    K get(int index) {