public function addProduct($dealId, array $data)
    {
        //if there is no product_id set throw error as it is a required field
        if (!isset($data['product_id'])) {
            throw new PipedriveMissingFieldError('You must include a "pdoruct_id" field when adding a product to a deal');
        }
        //if there is no item_price set throw error as it is a required field
        if (!isset($data['item_price'])) {
            throw new PipedriveMissingFieldError('You must include a "item_price" field when adding a product to a deal');
        }
        //if there is no quantity set throw error as it is a required field
        if (!isset($data['quantity'])) {
            throw new PipedriveMissingFieldError('You must include a "quantity" field when adding a product to a deal');
        }

        return $this->curl->post('deals/' . $dealId . '/products', $data);
    }