code: func (lb *LogBroker) Start(ctx context.Context) error {
  	lb.mu.Lock()
  	defer lb.mu.Unlock()
  
  	if lb.cancelAll != nil {
  		return errAlreadyRunning
  	}
  
  	lb.pctx, lb.cancelAll = context.WithCancel(ctx)
  	lb.logQueue = watch.NewQueue()
  	lb.subscriptionQueue = watch.NewQueue()
  	lb.registeredSubscriptions = make(map[string]*subscription)
  	lb.subscriptionsByNode = make(map[string]map[*subscription]struct{})
  	return nil
  }
docs: // Start starts the log broker