code: func (list *LinkedList) AddBack(entry interface{}) {
  	toAppend := &llNode{
  		payload: entry,
  	}
  
  	list.key.Lock()
  	defer list.key.Unlock()
  
  	list.length++
  
  	if list.first == nil {
  		list.first = toAppend
  		list.last = toAppend
  		return
  	}
  
  	list.last.next = toAppend
  	list.last = toAppend
  }
docs: // AddBack creates an entry in the LinkedList that is logically at the back of the list.