CampaignMonitor::getClientId PHP Method

    public function getClientId()
    {
        return (string) $this->clientId;
    }

 /**
  * class constructor
  * @param CampaignMonitor $monitor CampaignMonitor instance
  */
 public function __construct($monitor)
 {
     $this->monitor = $monitor;
     $this->auth = ['api_key' => $monitor->getApiKey()];
     $this->client = new \CS_REST_Clients($monitor->getClientId(), $this->auth);
 }