package module;
use strict;
use warnings;
sub handler {
    my $x = 23;
    sub inner {
        #my $x = $x;
        print "inner before: $x\n";
        $x = $x + 42;
        print "inner: $x\n";
    }
    inner();
}
package main;
module::inner();

ergebnis:
Variable "$x" will not stay shared at handler.pl line 9.
Use of uninitialized value in concatenation (.) or string at handler.pl line 9.
inner before: 
Use of uninitialized value in addition (+) at handler.pl line 10.
inner: 42