#!/usr/bin/perl -w
use strict;
package one;
require Exporter;
our @ISA = ("Exporter");
our @EXPORT = qw(foo);
sub foo {
    print "how do you do\n";
}

##</code><code>##

#!/usr/bin/perl -w
use strict;
package two;
require Exporter;
our @ISA = ("Exporter");
our @EXPORT = qw(foo);
sub foo {
    print "Salut toi! Ca va?\n";
}

##</code><code>##

#!/usr/bin/perl -w
use strict;
use one;
use two;
foo();

##</code><code>##

[~/] perl trial.pl 
Subroutine main::foo redefined at /usr/local/lib/perl5/5.8.2/Exporter.pm line 60.
 at trial.pl line 4
Salut toi! Ca va?

##</code><code>##

#!/usr/bin/perl -w
use strict;
use two;
use one;
foo();

##</code><code>##

[~/] perl trial.pl
Subroutine main::foo redefined at /usr/local/lib/perl5/5.8.2/Exporter.pm line 60.
 at trial.pl line 4
how do you do