original.put(1, "foo", 'a');
    assertSame(original.columnKeySet(), transpose.rowKeySet());
    assertSame(original.rowKeySet(), transpose.columnKeySet());
    assertSame(original.columnMap(), transpose.rowMap());
    assertSame(original.rowMap(), transpose.columnMap());
    assertSame(original.values(), transpose.values());
    assertEquals(original.row(1), transpose.column(1));
    assertEquals(original.row(2), transpose.column(2));

    Table<Integer, String, String> table = HashBasedTable.create();
    table.put(1, "foo", "apple");
    table.put(1, "bar", "banana");
    table.put(3, "foo", "cat");
    return transformValues(table, FIRST_CHARACTER).columnMap();
  }

  }

  @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) {

      columnBuilder.put(col.getKey(), ImmutableMap.copyOf(col.getValue()));
    }
    this.columnMap = columnBuilder.buildOrThrow();
  }

  @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() {

      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

    Table<Integer, String, Character> table = HashBasedTable.create();
    table.put(1, "foo", 'a');
    table.put(1, "bar", 'b');
    table.put(3, "foo", 'c');
    return unmodifiableTable(table).columnMap();
  }

        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) {

    original.put(1, "foo", 'a');
    assertSame(original.columnKeySet(), transpose.rowKeySet());
    assertSame(original.rowKeySet(), transpose.columnKeySet());
    assertSame(original.columnMap(), transpose.rowMap());
    assertSame(original.rowMap(), transpose.columnMap());
    assertSame(original.values(), transpose.values());
    assertEquals(original.row(1), transpose.column(1));
    assertEquals(original.row(2), transpose.column(2));