}

  @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) {

  }

  @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

      return Maps.transformValues(fromTable.rowMap(), row -> Maps.transformValues(row, function));
    }

    @Override
    public Map<C, Map<R, V2>> columnMap() {
      return Maps.transformValues(
          fromTable.columnMap(), column -> Maps.transformValues(column, function));
    }
  }

  /**
   * Returns an unmodifiable view of the specified table. This method allows modules to provide

        return false;
      }
    }
  }

  @LazyInit private transient @Nullable ColumnMap columnMap;

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

  @WeakOuter
  private final class ColumnMap extends ViewCachingAbstractMap<C, Map<R, V>> {

  }

  @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 Set<C> columnKeySet() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.columnKeySet();
    }

    @Override
    public Map<C, Map<R, V>> columnMap() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.columnMap();
    }

    @Override
    public boolean contains(Object rowKey, Object columnKey) {
      assertTrue(Thread.holdsLock(mutex));

    checkNotNull(columnKey);
    return containsColumn(columnKey)
        ? ImmutableMap.of(singleRowKey, singleValue)
        : ImmutableMap.<R, V>of();
  }

  @Override
  public ImmutableMap<C, Map<R, V>> columnMap() {
    return ImmutableMap.of(singleColumnKey, (Map<R, V>) ImmutableMap.of(singleRowKey, singleValue));
  }

  @Override
  public ImmutableMap<R, Map<C, V>> rowMap() {

  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() {

   *
   * <p>In contrast, the maps returned by {@code columnMap().get()} have the same behavior as those
   * returned by {@link #column}. Those maps may support {@code setValue()}, {@code put()}, and
   * {@code putAll()}.
   *
   * @return a map view from each column key to a secondary map from row keys to values
   */
  Map<C, Map<R, V>> columnMap();

  /**

/**
 * Implementation of {@link Table} using linked hash tables. This guarantees predictable iteration
 * order of the various views.
 *
 * <p>The views returned by {@link #column}, {@link #columnKeySet()}, and {@link #columnMap()} have
 * iterators that don't support {@code remove()}. Otherwise, all optional operations are supported.
 * Null row keys, columns keys, and values are not supported.
 *