docs: def close(self):
          """
          Closes all resources/backends associated with this queue manager.
          """
          self.log.info("Shutting down queue manager.")
          if hasattr(self.store, 'close'):
              self.store.close()
  
          if hasattr(self.subscriber_scheduler, 'close'):
              self.subscriber_scheduler.close()
  
          if hasattr(self.queue_scheduler, 'close'):
              self.queue_scheduler.close()