WC_Order::set_cart_hash PHP Method

    public function set_cart_hash($value)
    {
        $this->set_prop('cart_hash', $value);
    }

 /**
  * Create an order. Error codes:
  * 		520 - Cannot insert order into the database.
  * 		521 - Cannot get order after creation.
  * 		522 - Cannot update order.
  * 		525 - Cannot create line item.
  * 		526 - Cannot create fee item.
  * 		527 - Cannot create shipping item.
  * 		528 - Cannot create tax item.
  * 		529 - Cannot create coupon item.
  *
  * @throws Exception
  * @param  $data Posted data.
  * @return int|WP_ERROR
  */
 public function create_order($data)
 {
     // Give plugins the opportunity to create an order themselves.
     if ($order_id = apply_filters('woocommerce_create_order', null, $this)) {
         return $order_id;
     }
     try {
         $order_id = absint(WC()->session->get('order_awaiting_payment'));
         $cart_hash = md5(json_encode(wc_clean(WC()->cart->get_cart_for_session())) . WC()->cart->total);
         /**
          * If there is an order pending payment, we can resume it here so
          * long as it has not changed. If the order has changed, i.e.
          * different items or cost, create a new order. We use a hash to
          * detect changes which is based on cart items + order total.
          */
         if ($order_id && ($order = wc_get_order($order_id)) && $order->has_cart_hash($cart_hash) && $order->has_status(array('pending', 'failed'))) {
             // Action for 3rd parties.
             do_action('woocommerce_resume_order', $order_id);
             // Remove all items - we will re-add them later.
             $order->remove_order_items();
         } else {
             $order = new WC_Order();
         }
         foreach ($data as $key => $value) {
             if (is_callable(array($order, "set_{$key}"))) {
                 $order->{"set_{$key}"}($value);
             }
         }
         $order->set_created_via('checkout');
         $order->set_cart_hash($cart_hash);
         $order->set_customer_id(apply_filters('woocommerce_checkout_customer_id', get_current_user_id()));
         $order->set_currency(get_woocommerce_currency());
         $order->set_prices_include_tax('yes' === get_option('woocommerce_prices_include_tax'));
         $order->set_customer_ip_address(WC_Geolocation::get_ip_address());
         $order->set_customer_user_agent(wc_get_user_agent());
         $order->set_customer_note(isset($data['order_comments']) ? $data['order_comments'] : '');
         $order->set_payment_method($data['payment_method']);
         $order->set_shipping_total(WC()->cart->shipping_total);
         $order->set_discount_total(WC()->cart->get_cart_discount_total());
         $order->set_discount_tax(WC()->cart->get_cart_discount_tax_total());
         $order->set_cart_tax(WC()->cart->tax_total);
         $order->set_shipping_tax(WC()->cart->shipping_tax_total);
         $order->set_total(WC()->cart->total);
         $this->create_order_line_items($order);
         $this->create_order_fee_lines($order);
         $this->create_order_shipping_lines($order);
         $this->create_order_tax_lines($order);
         $this->create_order_coupon_lines($order);
         $order_id = $order->save();
         // Let plugins add their own meta data.
         do_action('woocommerce_checkout_update_order_meta', $order_id, $data);
         return $order_id;
     } catch (Exception $e) {
         return new WP_Error('checkout-error', $e->getMessage());
     }
 }