code: func (r *Ring) Peek() interface{} {
  	r.Lock()
  	defer r.Unlock()
  
  	r.checkInit()
  	if r.head == -1 {
  		return nil
  	}
  	return r.get(r.tail)
  }
docs: /*
  Read the value that Dequeue would have dequeued without actually dequeuing it.
  
  Returns nil if the ring buffer is empty.
  */