WC_Product::set_shipping_class_id PHP Method

    public function set_shipping_class_id($id)
    {
        $this->set_prop('shipping_class_id', absint($id));
    }

 /**
  * Save product shipping data
  *
  * @since 2.2
  * @param WC_Product $product
  * @param array $data
  * @return WC_Product
  */
 private function save_product_shipping_data($product, $data)
 {
     if (isset($data['weight'])) {
         $product->set_weight('' === $data['weight'] ? '' : wc_format_decimal($data['weight']));
     }
     // Product dimensions
     if (isset($data['dimensions'])) {
         // Height
         if (isset($data['dimensions']['height'])) {
             $product->set_height('' === $data['dimensions']['height'] ? '' : wc_format_decimal($data['dimensions']['height']));
         }
         // Width
         if (isset($data['dimensions']['width'])) {
             $product->set_width('' === $data['dimensions']['width'] ? '' : wc_format_decimal($data['dimensions']['width']));
         }
         // Length
         if (isset($data['dimensions']['length'])) {
             $product->set_length('' === $data['dimensions']['length'] ? '' : wc_format_decimal($data['dimensions']['length']));
         }
     }
     // Virtual
     if (isset($data['virtual'])) {
         $virtual = true === $data['virtual'] ? 'yes' : 'no';
         if ('yes' == $virtual) {
             $product->set_weight('');
             $product->set_height('');
             $product->set_length('');
             $product->set_width('');
         }
     }
     // Shipping class
     if (isset($data['shipping_class'])) {
         $data_store = $product->get_data_store();
         $shipping_class_id = $data_store->get_shipping_class_id_by_slug(wc_clean($data['shipping_class']));
         if ($shipping_class_id) {
             $product->set_shipping_class_id($shipping_class_id);
         }
     }
     return $product;
 }