mount method
当节点被关联时调用
Implementation
@protected
@mustCallSuper
void mount(ElLinkedList<N> list, N? prev, N? next) {
assert(
_list == null,
'ElLinkedNode Error: 节点已经挂载,不可重复关联链表!\n'
'$this',
);
_prev = prev;
_next = next;
_list = list;
list._length++;
}