public List<List<String>> cells() {
        return raw;
    }
@Test
    void cells_should_have_three_columns_and_two_rows() {
        List<List<String>> raw = createSimpleTable().cells();
        assertEquals(2, raw.size(), "Rows size");
        for (List<String> list : raw) {
            assertEquals(3, list.size(), "Cols size: " + list);
        }
    }