Fatal error: Call to undefined method WC_Product_Simple::get_available_variations() in sale-flash

I have added a sale code from (http://code.tutsplus.com/articles/customize-the-behavior-of-the-woocommerce-sale-flash--cms-22225) to (kutetheme/woocommerce/loop/sale-flash.php) but after saving all things going well but only the issue is appears in this url (http://www.aurlay.com/shop/home-kitchen/kitchen-dinning/cookwares/metal-finish/)

This is the error, i am facing right now...
Fatal error: Call to undefined method WC_Product_Simple::get_available_variations() in /home/aurlay/public_html/wp-content/themes/kutetheme/woocommerce/loop/sale-flash.php on line 16