layout in coding

$headBlock = $this->getLayout()->getBlock('head');
$headBlock->addJs('varien/product.js')
->addItem('js_css', 'calendar/calendar-win2k-1.css', null, null, 'can_load_calendar_js')
->addItem('js', 'calendar/calendar.js', null, null, 'can_load_calendar_js')
->addItem('js', 'calendar/calendar-setup.js', null, null, 'can_load_calendar_js')
->addItem('skin_js', 'js/bundle.js');
$this->renderLayout();