code: func (m *SubscriptionManager) Stop() {
  	if atomic.AddInt32(&m.stopped, 1) != 1 {
  		return
  	}
  
  	log.Debug("Stopping block notifications subscription manager")
  
  	close(m.quit)
  	m.wg.Wait()
  
  	var wg sync.WaitGroup
  	wg.Add(len(m.subscribers))
  	for _, subscriber := range m.subscribers {
  		go func() {
  			defer wg.Done()
  			subscriber.cancel()
  		}()
  	}
  
  	wg.Wait()
  }
docs: // Stop stops all active goroutines required for the SubscriptionManager to
  // carry out its duties.