$ perl -e 'use feature "say";
> {    my $number = 0;
>      sub supply_square {
>          $number ++;
>          return $number ** 2;
>      }
> }
> say supply_square for 1..5;
> say supply_square for 1..5; '
1
4
9
16
25
36
49
64
81
100