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() {
    Set<Cell<R, C, V>> result = 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() {
    Set<Cell<R, C, V>> result = cellSet;

                      @SuppressWarnings("unchecked")
                      Cell<String, Integer, Character> cell =
                          (Cell<String, Integer, Character>) element;
                      columnKeys.add(cell.getColumnKey());
                    }
                    Table<String, Integer, Character> table =
                        ArrayTable.create(ImmutableList.of("bar"), columnKeys);
                    for (Object element : elements) {

    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)
        ? ImmutableMap.of(singleRowKey, singleValue)

      final int columnIndex = index % columnList.size();

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

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

      @Override
      public @Nullable V getValue() {
        return at(rowIndex, columnIndex);
      }
    };
  }