public static Formatter forDates(@Nonnull String format) {
        return new DateFormat(format);
    }
@Test
    public void testWeekDates() {
        Formatter f = forDates("IYYY-\"W\"IW-FMID");
        check(LocalDate.of(2022, 10, 25), f, "2022-W43-2");
        check(LocalDate.of(2019, 12, 30), f, "2020-W01-1");

        f = forDates("YYYY-MM-DD \"is the\" FMIDDDth \"day of week-year\" FMIYYY.");
        check(LocalDate.of(2008, 12, 29), f, "2008-12-29 is the 1st day of week-year 2009.");
        check(LocalDate.of(2010, 1, 3), f, "2010-01-03 is the 371st day of week-year 2009.");

        f = forDates("IYYY IYY IY I - FMIYYY FMIYY FMIY FMI");
        check(LocalDate.of(1, 1, 1), f, "0001 001 01 1 - 1 1 1 1");
    }