$definition = new Definition(
    [],
    [
        new Transition('start', 'init', [new Arc('prepare_leg', 4), 'prepare_top', 'stopwatch_running']),
        new Transition('build_leg', 'prepare_leg', 'leg_created'),
        new Transition('build_top', 'prepare_top', 'top_created'),
        new Transition('join', [new Arc('leg_created', 4), 'top_created', 'stopwatch_running'], 'finished'),
    ]
);

$subject = new Subject();
$workflow = new Workflow($definition);

$workflow->apply($subject, 'start');

$workflow->apply($subject, 'build_leg');
$workflow->apply($subject, 'build_top');
$workflow->apply($subject, 'build_leg');
$workflow->apply($subject, 'build_leg');
$workflow->apply($subject, 'build_leg');
$workflow->apply($subject, 'join');