presto-main/src/main/java/io/prestosql/operator/scalar/DateTimeFunctions.java/DateTimeFunctions/addFieldValueTimeWithTimeZone
class DateTimeFunctions:    @Description("add the specified amount of time to the given time")
    @LiteralParameters("x")
    @ScalarFunction("date_add")
    @SqlType(StandardTypes.TIME_WITH_TIME_ZONE)
    public static long addFieldValueTimeWithTimeZone(
            @SqlType("varchar(x)") Slice unit,
            @SqlType(StandardTypes.BIGINT) long value,
            @SqlType(StandardTypes.TIME_WITH_TIME_ZONE) long timeWithTimeZone)
    {
        ISOChronology chronology = unpackChronology(timeWithTimeZone);
        long millis = modulo24Hour(chronology, getTimeField(chronology, unit).add(unpackMillisUtc(timeWithTimeZone), toIntExact(value)));
        return updateMillisUtc(millis, timeWithTimeZone);
    }