### my-perl-script.pl
use strict;
use warnings;
use Bar;

use subs qw(foo);
foo;


sub foo {
    print "Foo, from the main package.\n";
}

##</code><code>##

### Bar.pm
package Bar;
use strict;
use warnings;


sub foo {
    print "Also foo, but this comes from the Bar package.\n";
    print "(And no, if my wife calls, I'm not at the bar!)\n";
}