}

  @LazyInit private transient @Nullable ColumnMap columnMap;

  @Override
  public Map<C, Map<R, @Nullable V>> columnMap() {
    ColumnMap map = columnMap;
    return (map == null) ? columnMap = new ColumnMap() : map;
  }

  @WeakOuter
  private final class ColumnMap extends ArrayMap<C, Map<R, @Nullable V>> {
    private ColumnMap() {
      super(columnKeyToIndex);
    }

    @Override

  }

  @Override
  public boolean containsColumn(@Nullable Object columnKey) {
    return Maps.safeContainsKey(columnMap(), columnKey);
  }

  @Override
  public Set<R> rowKeySet() {
    return rowMap().keySet();
  }

  @Override
  public Set<C> columnKeySet() {
    return columnMap().keySet();
  }

  @Override
  public boolean containsValue(@Nullable Object value) {

  }

  public void testColumnKeySet() {
    assertEquals(ImmutableSet.of(), INSTANCE.columnKeySet());
  }

  public void testColumnMap() {
    assertEquals(ImmutableMap.of(), INSTANCE.columnMap());
  }

  public void testContains() {
    assertFalse(INSTANCE.contains('a', 1));
  }

  public void testContainsColumn() {
    assertFalse(INSTANCE.containsColumn(1));
  }

  public void testColumnKeySet() {
    assertEquals(ImmutableSet.of(1), testTable.columnKeySet());
  }

  public void testColumnMap() {
    assertEquals(ImmutableMap.of(1, ImmutableMap.of('a', "blah")), testTable.columnMap());
  }

  public void testRow() {
    assertEquals(ImmutableMap.of(), testTable.row('A'));
    assertEquals(ImmutableMap.of(1, "blah"), testTable.row('a'));
  }

  public void testRowKeySet() {

      assertEquals(
          ImmutableMap.of(
              1, ImmutableMap.of('a', "foo", 'b', "bar"), 2, ImmutableMap.of('a', "baz")),
          testInstance.columnMap());
    }
  }

  public void testContains() {
    for (ImmutableTable<Character, Integer, String> testInstance : getTestInstances()) {
      assertTrue(testInstance.contains('a', 1));