code: func (m *SubscriptionManager) Start() {
  	if atomic.AddInt32(&m.started, 1) != 1 {
  		return
  	}
  
  	log.Debug("Starting block notifications subscription manager")
  
  	m.wg.Add(1)
  	go m.subscriptionHandler()
  }
docs: // Start starts all the goroutines required for the SubscriptionManager to carry
  // out its duties.