public function product($invoiceLineHandle, $product)
    {
        $products = new Product($this->client_raw);
        $productHandle = $products->getHandle($product);

        $this->client
            ->CurrentInvoiceLine_SetProduct(
                array(
                    'currentInvoiceLineHandle' => $invoiceLineHandle,
                    'valueHandle' => $productHandle
                )
            );

        return true;
    }