#!perl

use strict;
use warnings;

use M;
use X;

hello("world");
bye();

##</code><code>##

package M;

require Exporter;
@ISA = (Exporter);
@EXPORT = qw(hello);

use warnings;
use strict;

sub hello {
  print "Hello @_!\n";
}

##</code><code>##

package X;

require Exporter;
@ISA = (Exporter);
@EXPORT = qw(bye);

use warnings;
use strict;

sub bye {
  M::hello("again"); # if exists M:hello();
  print "That's all, folks!\n";
}