use Devel::Peek;
use Readonly;

Readonly::Scalar  my $number => 10;

Dump($number);
printf "Number is %d\n", $number;
Dump($number);
print "Number is $number\n";
Dump($number);

##</code><code>##

use Devel::Peek;
use Scalar::Readonly ':all';

my $number = 10;
readonly_on($number);

Dump($number);
print "Number is $number\n";
Dump($number);