sub append_stuff {
  my ($input) = @_;
  $input . "stuff";
}

##</code><code>##

sub modify_stuff {
   $_[0] .= "stuff";
}

##</code><code>##

my $input = "some";
print append_stuff($input),"\n";
print "$input\n";
print modify_stuff($input),"\n";
print "$input\n";
__END__
somestuff
some
somestuff
somestuff

##</code><code>##

my $input = "some";
print s/ome/tuff/;
print $input;
__END__
1stuff