#!usr/bin/perl
use strict;
use warnings;

sub sub1{return 2}
sub sub2{return 2}

my ($a, $b) = (sub1, sub2);
my ($s, $t) = ((2*sub1()+sub2()), (2*$a+$b));


say STDERR "$a==", sub1;
say STDERR "$b==", sub2;
say STDERR "$s==$t";

__END__
2==2
2==2
6==6