code: func (c *CheckTTL) Start() {
  	c.stopLock.Lock()
  	defer c.stopLock.Unlock()
  	c.stop = false
  	c.stopCh = make(chan struct{})
  	c.timer = time.NewTimer(c.TTL)
  	go c.run()
  }
docs: // Start is used to start a check ttl, runs until Stop()