sub do_step_one {
  print "  step one: $_[ARG0]\n";
  $_[KERNEL]->yield('step_two', $_[ARG0]) if rand(1) > 0.5;
  $_[KERNEL]->yield('process_next_input') if $poe_kernel->get_event_count() == 0;
}

sub do_step_two {
  print "  step two: $_[ARG0]\n";
  $_[KERNEL]->yield('process_next_input') if $poe_kernel->get_event_count() == 0;
}