use strict;
use warnings;

main();                                                # <----- change here

sub main {                                             # <----- change here
    my $foo = 5;
    
    print "Content-type: text/plain\n";
    print "Content-disposition: inline; filename=foo.txt\n\n";
    
    printf "Package: %s\n", __PACKAGE__;
    printf "[%s] Before: %s\n", $$, $foo;
    badness(5);
    printf "[%s] After: %s\n", $$, $foo;
}                                                      # <----- change here

sub badness {
    my $val = shift;
    printf "[%s] badness: %s\n", $$, $foo;
    $foo += $val;

}