package A;
use vars qw{$VERSION @ISA @EXPORT @EXPORT_OK};
require Exporter;
@ISA = qw(Exporter);
@EXPORT = qw(&a);
use strict;

sub a;

sub a {
 $a = $_[0];
 defined $a or $a='a';
 print $a;
}

1;
##</code><code>##

#!/usr/bin/perl -Tw
use lib 'where/a/pm/resides';
use strict;
use A;

a;

exit;

##</code><code>##

package B;
use vars qw{$VERSION @ISA @EXPORT @EXPORT_OK};
require Exporter;
@ISA = qw(Exporter);
@EXPORT = qw(&b);
use strict;
use A;

sub b;

sub b {
 a;
}

1;

##</code><code>##

#!/usr/bin/perl -Tw
use lib 'where/a/pm/resides';
use strict;
use A;
use B;

a;

b;

exit;