package MyModule;

use warnings;
use strict;

print __PACKAGE__, ' called from ', (caller)[1], ".\n";

sub func {
    return 2 * shift
}

__PACKAGE__

##</code><code>##

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

use MyModule;
warn MyModule::func(21);

##</code><code>##

MyModule called from ./script.pl.
42 at ./script.pl line 8.