Object writeReplace() {
      return super.writeReplace();
    }
  }

  @Override
  public ImmutableMap<C, Map<R, V>> columnMap() {
    // Casts without copying.
    ImmutableMap<C, ImmutableMap<R, V>> columnMap = this.columnMap;
    return ImmutableMap.<C, Map<R, V>>copyOf(columnMap);
  }

  @Override
  public ImmutableMap<R, Map<C, V>> rowMap() {
    // Casts without copying.

    Object writeReplace() {
      return super.writeReplace();
    }
  }

  @Override
  public ImmutableMap<C, Map<R, V>> columnMap() {
    // Casts without copying.
    ImmutableMap<C, ImmutableMap<R, V>> columnMap = this.columnMap;
    return ImmutableMap.<C, Map<R, V>>copyOf(columnMap);
  }

  @Override
  public ImmutableMap<R, Map<C, V>> rowMap() {
    // Casts without copying.

    @Override
    public Map<C, Map<R, V2>> columnMap() {
      Function<Map<R, V1>, Map<R, V2>> columnFunction =
          new Function<Map<R, V1>, Map<R, V2>>() {
            @Override
            public Map<R, V2> apply(Map<R, V1> column) {
              return Maps.transformValues(column, function);
            }
          };
      return Maps.transformValues(fromTable.columnMap(), columnFunction);
    }
  }

  /**

  }

  @LazyInit @CheckForNull private transient ColumnMap columnMap;

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

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

    @Override

    checkNotNull(columnKey, "columnKey");
    return MoreObjects.firstNonNull(
        (ImmutableMap<R, V>) columnMap().get(columnKey), ImmutableMap.<R, V>of());
  }

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

  /**
   * {@inheritDoc}
   *

   *
   * <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();

  /**

   *
   * <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();

  /**

      table.put(1, "foo", 'a');
      table.put(1, "bar", 'b');
      table.put(3, "foo", 'c');
      return table.columnMap();
    }

    @Override
    protected Map<String, Map<Integer, Character>> makeEmptyMap() {
      return makeTable().columnMap();
    }
  }

      table.put(1, "foo", 'a');
      table.put(1, "bar", 'b');
      table.put(3, "foo", 'c');
      return table.columnMap();
    }

    @Override
    protected Map<String, Map<Integer, Character>> makeEmptyMap() {
      return makeTable().columnMap();
    }
  }

 * returns a {@link SortedMap}, instead of the {@link Set} and {@link Map} specified by the {@link
 * Table} interface.
 *
 * <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.
 *