presto-main/src/main/java/io/prestosql/operator/scalar/DateTimeFunctions.java/DateTimeFunctions/timeZoneHourFromTimestampWithTimeZone
class DateTimeFunctions:    @Description("time zone hour of the given timestamp")
    @ScalarFunction("timezone_hour")
    @SqlType(StandardTypes.BIGINT)
    public static long timeZoneHourFromTimestampWithTimeZone(@SqlType(StandardTypes.TIMESTAMP_WITH_TIME_ZONE) long timestampWithTimeZone)
    {
        return extractZoneOffsetMinutes(timestampWithTimeZone) / 60;
    }