@ConstantFunction.List(list = {
            @ConstantFunction(name = "adddate", argTypes = {DATETIME, INT}, returnType = DATETIME, isMonotonic = true),
            @ConstantFunction(name = "date_add", argTypes = {DATETIME, INT}, returnType = DATETIME, isMonotonic = true),
            @ConstantFunction(name = "days_add", argTypes = {DATETIME, INT}, returnType = DATETIME, isMonotonic = true)
    })
    public static ConstantOperator daysAdd(ConstantOperator date, ConstantOperator day) {
        return ConstantOperator.createDatetimeOrNull(date.getDatetime().plusDays(day.getInt()));
    }
@Test
    public void daysAdd() {
        assertEquals("2015-04-02T09:23:55",
                ScalarOperatorFunctions.daysAdd(O_DT_20150323_092355, O_INT_10).getDatetime().toString());
    }