presto-main/src/main/java/io/prestosql/operator/scalar/DateTimeFunctions.java/DateTimeFunctions/hourFromInterval
class DateTimeFunctions:    @Description("hour of the day of the given interval")
    @ScalarFunction("hour")
    @SqlType(StandardTypes.BIGINT)
    public static long hourFromInterval(@SqlType(StandardTypes.INTERVAL_DAY_TO_SECOND) long milliseconds)
    {
        return (milliseconds % MILLISECONDS_IN_DAY) / MILLISECONDS_IN_HOUR;
    }