#!/usr/bin/perl

use warnings;
use strict;

sub callback {
    for my $n (1..3){
        print "callback: $n\n";
        sleep(1);
    }
}

sub my_caller {
    my ($i, $func) = @_;
    print "caller calling callback\n";
    &$func();
}

# main

my_caller(10, \&callback);

for my $n (10..12){
    print "main: $n\n";
    sleep(1)
}