#!/usr/bin/perl -w
use strict;
use warnings;

sub foo{
my $code = shift;

<<"END_MSG";
Add the code
$code
END_MSG
}

my $code=<<'END_MSG';
line 1
line2
END_MSG

print "before calling\n";
print $code;

print "after calling\n";
print foo($code);

print "why blank line above?\n";

##</code><code>##

perl t2.pl 

before calling
line 1
line2
after calling
Add the code
line 1
line2

why blank line above?

##</code><code>##

perl>perl -v

This is perl 5, version 18, subversion 2 (v5.18.2) built for x86_64-linux-gnu-thread-multi
(with 41 registered patches, see perl -V for more detail)