* @throws IllegalArgumentException if the size of {@code data} isn't a multiple of 3
   * @throws ClassCastException if a data element has the wrong type
   */
  protected abstract Table<String, Integer, C> create(@Nullable Object... data);

  protected void assertSize(int expectedSize) {
    assertEquals(expectedSize, table.size());
  }

  @Override

   * @throws IllegalArgumentException if the size of {@code data} isn't a multiple of 3
   * @throws ClassCastException if a data element has the wrong type
   */
  protected abstract Table<String, Integer, C> create(@Nullable Object... data);

  protected void assertSize(int expectedSize) {
    assertEquals(expectedSize, table.size());
  }

  @Override