script
-> A::a_func("str") 
-> B::b_func("str") 
-> C::c_func("str") # c_func is what prints the data

##</code><code>##

use warnings;
use strict;

use lib '.';

use A qw(a_func);

a_func("a string");

##</code><code>##

package A;

use lib '.';

use B qw(b_func); # load the 'B' package

use Exporter qw(import);
our @EXPORT_OK = qw(a_func);

sub a_func {
    my $str = shift;
    b_func($str);
}

1;

##</code><code>##

package B;

use lib '.';

use C qw(c_func);

use Exporter qw(import);

our @EXPORT_OK = qw (b_func);

sub b_func {
    my $str = shift;
    c_func($str);
}

1;

##</code><code>##

package C;

use Exporter qw(import);

our @EXPORT_OK = qw(c_func);

sub c_func {
    my $string_to_say = shift;
    print "$string_to_say\n";
}

1;