test.pl
------
#!/usr/bin/perl -w

use strict;
use test_module;

my $var=10;
my $new_var=testsub($var);
print "$new_var\n";


##</code><code>##


test_module.pm
-----------------------
sub testsub
{
	my $in_arg=@_;
	my $new_arg=$in_arg+10;
	return($new_arg);
}

1;