@ConstantFunction(name = "hours_sub", argTypes = {DATETIME, INT}, returnType = DATETIME, isMonotonic = true)
    public static ConstantOperator hoursSub(ConstantOperator date, ConstantOperator hour) {
        return ConstantOperator.createDatetimeOrNull(date.getDatetime().minusHours(hour.getInt()));
    }
@Test
    public void hoursSub() {
        assertEquals("2015-03-22T23:23:55",
                ScalarOperatorFunctions.hoursSub(O_DT_20150323_092355, O_INT_10).getDatetime().toString());
    }