Table<C, R, V> transpose(Table<R, C, V> table) {
    return (table instanceof TransposeTable)
        ? ((TransposeTable<R, C, V>) table).original
        : new TransposeTable<C, R, V>(table);
  }

  private static final class TransposeTable<
          C extends @Nullable Object, R extends @Nullable Object, V extends @Nullable Object>
      extends AbstractTable<C, R, V> {