* @param  array  $cart_item
     * @return boolean
     */
    public static function is_convertible_to_sub($cart_item)
    {
        $product_id = $cart_item['product_id'];
        $is_convertible = true;
        if (WC_Subscriptions_Product::is_subscription($product_id)) {
            $is_convertible = false;
        }
        return $is_convertible;
    }
    /**
     * True if the product corresponding to a cart item is one of the types supported by the plugin.
     *
     * @param  array  $cart_item
     * @return boolean
     */
    public static function is_supported_product_type($cart_item)
    {
        $product = $cart_item['data'];
        $product_type = $cart_item['data']->product_type;
        $supported_types = WCS_ATT()->get_supported_product_types();
        if (in_array($product_type, $supported_types)) {
            return true;
        }
        return false;
    }
}
WCS_ATT_Cart::init();