code: func (bee *Bee) Stop() {
  	if !bee.IsRunning() {
  		return
  	}
  	log.Println(bee.Name(), "stopping gracefully!")
  
  	close(bee.SigChan)
  	bee.waitGroup.Wait()
  	bee.Running = false
  	log.Println(bee.Name(), "stopped gracefully!")
  }
docs: // Stop gracefully stops a Bee.