#!/usr/bin/perl

use strict;
use warnings;

BEGIN {
    if    ( $^O =~ /dar/ ) { require mac; mac -> import; }
    elsif ( $^O =~ /sol/ ) { require sun; sun -> import; }
    elsif ( $^O =~ /aix/ ) { require aix; aix -> import; }
    else                   { die "unknown os." }
};

print "answer is " . get_answer () . "\n";
__END__