func (list *LinkedList) IsEmpty() bool {
	list.key.RLock()
	defer list.key.RUnlock()

	return list.first == nil
}
func (list *LinkedList) IsEmpty() bool {
	list.key.RLock()
	defer list.key.RUnlock()

	return list.first == nil
}
// IsEmpty tests the list to determine if it is populate or not.