collector = toImmutableTable(Cell::getRowKey, Cell::getColumnKey, t -> null);
      assertThrows(
          NullPointerException.class,
          () -> Stream.of(immutableCell("one", "uno", 1)).collect(collector));
    }
    {
      Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>>
          collector = toImmutableTable(Cell::getRowKey, Cell::getColumnKey, Cell::getValue);
      assertThrows(

  }

  @Override
  public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
    for (Table.Cell<? extends R, ? extends C, ? extends V> cell : table.cellSet()) {
      put(cell.getRowKey(), cell.getColumnKey(), cell.getValue());
    }
  }

  @LazyInit private transient @Nullable Set<Cell<R, C, V>> cellSet;

  @Override
  public Set<Cell<R, C, V>> cellSet() {

  }

  @Override
  public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
    for (Table.Cell<? extends R, ? extends C, ? extends V> cell : table.cellSet()) {
      put(cell.getRowKey(), cell.getColumnKey(), cell.getValue());
    }
  }

  @LazyInit private transient @Nullable Set<Cell<R, C, V>> cellSet;

  @Override
  public Set<Cell<R, C, V>> cellSet() {

        Cell<?, ?, ?> other = (Cell<?, ?, ?>) obj;
        return Objects.equals(getRowKey(), other.getRowKey())
            && Objects.equals(getColumnKey(), other.getColumnKey())
            && Objects.equals(getValue(), other.getValue());
      }
      return false;
    }

    @Override
    public int hashCode() {
      return Objects.hash(getRowKey(), getColumnKey(), getValue());
    }

    @Override

                      @SuppressWarnings("unchecked")
                      Cell<String, Integer, Character> cell =
                          (Cell<String, Integer, Character>) element;
                      table.put(cell.getRowKey(), cell.getColumnKey(), cell.getValue());
                    }
                    return table.cellSet();
                  }

                  @Override

    this.singleRowKey = checkNotNull(rowKey);
    this.singleColumnKey = checkNotNull(columnKey);
    this.singleValue = checkNotNull(value);
  }

  SingletonImmutableTable(Cell<R, C, V> cell) {
    this(cell.getRowKey(), cell.getColumnKey(), cell.getValue());
  }

  @Override
  public ImmutableMap<R, V> column(C columnKey) {
    checkNotNull(columnKey);
    return containsColumn(columnKey)

   * @since 7.0
   */
  interface Cell<
      R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object> {
    /** Returns the row key of this cell. */
    @ParametricNullness
    R getRowKey();

    /** Returns the column key of this cell. */
    @ParametricNullness
    C getColumnKey();

    /** Returns the value of this cell. */
    @ParametricNullness
    V getValue();

    /**

    return new Tables.AbstractCell<R, C, @Nullable V>() {
      final int rowIndex = index / columnList.size();
      final int columnIndex = index % columnList.size();

      @Override
      public R getRowKey() {
        return rowList.get(rowIndex);
      }

      @Override
      public C getColumnKey() {
        return columnList.get(columnIndex);
      }

      @Override