use warnings;
use strict;

use constant duh => 0;
my $y = "X"   if duh;
sub x{ 
    print $y ? 'Okay' : 'bad';
}

x();
print "$y\n";

##</code><code>##

use warnings;
use strict;

my $y = "X"   if 0;
sub x{ 
    print $y ? 'Okay' : 'bad';
}

x();
print "$y\n";