select  location, age, avg(income), min(income), max(income) from Person group by location, age  //SQL

acc( $p : Person();
        [$l, $a] : distinct( $p.location, $p.age) )
acc( $p : Person( location == $l, age == $a );
       $avgIncome : avg( $p.income ) ,
       $minIncome : min( $p.income ),
       $maxIncome : max( $p.income ) )

If we wanted to make a  list of lists we could add:

acc( $l : List() from [$avgIncome, $minIncome, $maxIncome],

       list( $l )

Can some give me specific example with this