@ConstantFunction(name = "weeks_add", argTypes = {DATETIME, INT}, returnType = DATETIME, isMonotonic = true)
    public static ConstantOperator weeksAdd(ConstantOperator date, ConstantOperator week) {
        return ConstantOperator.createDatetimeOrNull(date.getDatetime().plusWeeks(week.getInt()));
    }
@Test
    public void weeksAdd() {
        assertEquals("2015-06-01T09:23:55",
                ScalarOperatorFunctions.weeksAdd(O_DT_20150323_092355, O_INT_10).getDatetime().toString());
    }