How to write subroutine which gives reference of its argument.

refsub.pl

#!/usr/bin/perl

use strict;
use warnings;

# chomp2
# Is this chomp?
# chomp erases only ONE "\n" on end of scalar.
# chomp2 erases ALL continuous "\n" on end of scalar.
sub chomp2 (\$) {
    my $str_ref = shift;
    warn "chomp2: arg is $str_ref\n";
    $$str_ref =~ s/(\n+)\z//;
    return $1;
}

my $text = "mogemoge\nfuga\n\n";

chomp2 $text;

print qq{"$text"\n};