sub aa(){2}
sub bb(){2}

my ($a, $b) = (aa, bb);
my ($s, $t) = ((2*aa+bb), (2*$a+$b));

say STDERR "$a==", aa;
say STDERR "$b==", bb;
say STDERR "$s==$t";

##</code><code>##

2==2
2==2
6==6