code: public function init($adapter, $client = null)
      {
          // set the server adapter
          $this->adapter = $adapter;
  
          // for ease of use we can fallback to a default http client
          if (!$client) {
              $client = new \PeterColes\Cluster\HttpClients\GuzzleHttp;
          }
  
          // initialise the http client with the authentication header options
          $client->initClient($this->adapter->getHeaders());
  
          // make the initialised http client available to the adapter
          $this->adapter->setClient($client);
      }
docs: Initialise the adapter, including injecting an http client
  
  @param object $adapter
  @param object $client
  @return void