use strict;
use warnings;

sub modify_args {
  $_[0] = 'new-value';
}

my ($one, $two) = qw(cat dog);

modify_args($one, $two);

print "$one $two\n";

##</code><code>##

sub modify_args1 {
  my ($argref1, $argref2) = \(@_[0..$#_]);
  $$argref1 = 'new value';
}