code: func (r *Runner) Start() {
  	r.lock.Lock()
  	defer r.lock.Unlock()
  	if r.stop == nil {
  		c := make(chan struct{})
  		r.stop = &c
  		for i := range r.loopFuncs {
  			go r.loopFuncs[i](*r.stop)
  		}
  	}
  }
docs: // Start begins running.