use Module 1.23;

##</code><code>##

$ perl -e'use Carp 100 ()'
Carp version 100 required--this is only version 1.26 at -e line 1.
BEGIN failed--compilation aborted at -e line 1.

$ perl -e'use Carp () => 100'
Carp version 100 required--this is only version 1.26 at /home/tai/perl5/perlbrew/perls/perl-5.16.2/lib/5.16.2/Exporter/Heavy.pm line 120.
BEGIN failed--compilation aborted at -e line 1.

##</code><code>##

use Readonly my $unprintable => 0x15;

##</code><code>##

use Readonly undef => 0x15;