}

  /**
   * {@inheritDoc}
   *
   * @throws NullPointerException if {@code columnKey} is {@code null}
   */
  @Override
  public ImmutableMap<R, V> column(C columnKey) {
    checkNotNull(columnKey, "columnKey");
    return MoreObjects.firstNonNull(
        (ImmutableMap<R, V>) columnMap().get(columnKey), ImmutableMap.<R, V>of());
  }

  @Override
  public ImmutableSet<C> columnKeySet() {

    return containsRow(rowKey) && containsColumn(columnKey);
  }

  /**
   * Returns {@code true} if the provided column key is among the column keys provided when the
   * table was constructed.
   */
  @Override
  public boolean containsColumn(@Nullable Object columnKey) {
    return columnKeyToIndex.containsKey(columnKey);
  }

  /**

        @ParametricNullness C columnKey,
        @ParametricNullness V value) {
      this.rowKey = rowKey;
      this.columnKey = columnKey;
      this.value = value;
    }

    @Override
    @ParametricNullness
    public R getRowKey() {
      return rowKey;
    }

    @Override
    @ParametricNullness
    public C getColumnKey() {
      return columnKey;
    }

    @Override

  }

  /**
   * {@inheritDoc}
   *
   * @throws NullPointerException if {@code columnKey} is {@code null}
   */
  @Override
  public ImmutableMap<R, V> column(C columnKey) {
    checkNotNull(columnKey, "columnKey");
    return MoreObjects.firstNonNull(
        (ImmutableMap<R, V>) columnMap().get(columnKey), ImmutableMap.<R, V>of());
  }

  @Override
  public ImmutableSet<C> columnKeySet() {

  @Override
  public Map<R, V> column(C columnKey) {
    return new Column(columnKey);
  }

  private final class Column extends ViewCachingAbstractMap<R, V> {
    final C columnKey;

    Column(C columnKey) {
      this.columnKey = checkNotNull(columnKey);
    }

    @Override
    public @Nullable V put(R key, V value) {
      return StandardTable.this.put(key, columnKey, value);
    }

    @Override

   *
   * @param rowKey key of row to search for
   * @param columnKey key of column to search for
   */
  boolean contains(
      @CompatibleWith("R") @Nullable Object rowKey,
      @CompatibleWith("C") @Nullable Object columnKey);

  /**
   * Returns {@code true} if the table contains a mapping with the specified row key.
   *

 *
 * <p>Lookups by row key are often faster than lookups by column key, because the data is stored in
 * a {@code Map<R, Map<C, V>>}. A method call like {@code column(columnKey).get(rowKey)} still runs
 * quickly, since the row key is provided. However, {@code column(columnKey).size()} takes longer,
 * since an iteration across all row keys occurs.
 *
 * <p>Because a {@code TreeBasedTable} has unique sorted values for a given row, both {@code

 *
 * <p>Lookups by row key are often faster than lookups by column key, because the data is stored in
 * a {@code Map<R, Map<C, V>>}. A method call like {@code column(columnKey).get(rowKey)} still runs
 * quickly, since the row key is provided. However, {@code column(columnKey).size()} takes longer,
 * since an iteration across all row keys occurs.
 *
 * <p>Because a {@code TreeBasedTable} has unique sorted values for a given row, both {@code

                    List<Integer> columnKeys = new ArrayList<>();
                    for (Object element : elements) {
                      @SuppressWarnings("unchecked")
                      Cell<String, Integer, Character> cell =
                          (Cell<String, Integer, Character>) element;
                      columnKeys.add(cell.getColumnKey());
                    }