code: func (eq *Queue) Write(event Event) error {
  	eq.mu.Lock()
  	defer eq.mu.Unlock()
  
  	if eq.closed {
  		return ErrSinkClosed
  	}
  
  	eq.events.PushBack(event)
  	eq.cond.Signal() // signal waiters
  
  	return nil
  }
docs: // Write accepts the events into the queue, only failing if the queue has
  // been closed.