public function updateCustomer($customer_id)
    {
        $data = [
            "email" => request()->email,
            "first_name" => request()->fname,
            "last_name" => request()->lname,
            "phone" => request()->phone,
            "metadata" => request()->additional_info /* key => value pairs array */

        ];

        $this->setRequestOptions();
        return $this->setHttpResponse('/customer/'. $customer_id, 'PUT', $data)->getResponse();
    }