my $data = $self->cmd('show run', undef, $output_ref, qr/^(?![:!])/);
$data .= 'appended data';
# Equivalent to
$data = $data . 'appended data';

##</code><code>##

my $data = $self->cmd('show run', undef, $output_ref, qr/^(?![:!])/);
$data .= $self->cmd('some other command', undef, $output_ref, qr/^(?![:!])/);

##</code><code>##

use strict;
use warnings;

sub something { return (3,4,5) };

my $x = 'some data'; #scalar
$x .= something; #list

print $x;
# some data5

print "\n";
print something;
# 345