@ConstantFunction(name = "years_sub", argTypes = {DATETIME, INT}, returnType = DATETIME, isMonotonic = true)
    public static ConstantOperator yearsSub(ConstantOperator date, ConstantOperator year) {
        return ConstantOperator.createDatetimeOrNull(date.getDatetime().minusYears(year.getInt()));
    }
@Test
    public void yearsSub() {
        assertEquals("2005-03-23T09:23:55",
                ScalarOperatorFunctions.yearsSub(O_DT_20150323_092355, O_INT_10).getDatetime().toString());
    }