code: public function init()
      {
          if ($this->isInitialized())
              return true;
  
          // attach default listeners
          /** @var $sharedEvents \Zend\EventManager\SharedEventManager */
          $sm = $this->getServiceManager();
          $defaultListeners = $sm->get('yimaTheme.Manager.ListenerAggregate');
          if ($defaultListeners instanceof self)
              // inject themeManager
              $defaultListeners->manager = $this;
  
          $sharedEvents = $this->getEventManager()->getSharedManager();
          $sharedEvents->attachAggregate($defaultListeners);
  
          $this->isInitialized = true;
  
          return $this;
      }
docs: Init Theme Manager To Work
  
  @return $this