有这么一段代码
data work.totalsales;
   set work.monthlysales(keep=year product sales);
   retain monthsales{12};
   array monthsales{12};
      do i=1 to 12;
         monthsales{i}=sales;
      end;
   cnt+1;
   monthsales{cnt}=sales;
run;
/*The data set named Work.Monthlysales has one observation per month for each of five years for a total of 60 observations.*/虽然他有错误，但是它有意图，但是我怎么也不明白这段代码的意图是什么，求助一下大虾们帮忙看看~~