public function generatePdf(Template $template)
 {
     $guzzleclient = new GuzzleClient();
     $res = $guzzleclient->post($this->url . '/api/v1', ['auth' => [$this->user, $this->password], 'headers' => ['content-type' => 'application/json'], 'body' => $template->serialize()]);
     if ($res->getStatusCode() == 201) {
         return json_decode($res->getBody(), true)['id'];
     }
 }