@ConstantFunction(name = "hours_add", argTypes = {DATETIME, INT}, returnType = DATETIME, isMonotonic = true)
    public static ConstantOperator hoursAdd(ConstantOperator date, ConstantOperator hour) {
        return ConstantOperator.createDatetimeOrNull(date.getDatetime().plusHours(hour.getInt()));
    }
@Test
    public void hoursAdd() {
        assertEquals("2015-03-23T19:23:55",
                ScalarOperatorFunctions.hoursAdd(O_DT_20150323_092355, O_INT_10).getDatetime().toString());
    }