code: public function payload(array $payload)
      {
          $client = new GuzzleClient([
              'base_uri' => $this->server
          ]);
          $client->request('POST', $this->getUri(), [
              'form_params' => [
                  'payload' => json_encode($payload)
              ]
          ]);
      }
docs: Sends a payload to the server.
  @param array $payload