linkedlist.go
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
}
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
}
// AddBack creates an entry in the LinkedList that is logically at the back of the list.