如何使用通过引用传递的值进行更新以删除双链接列表中的出现次数

我正在使用双向链表，并试图根据用户的输入删除节点。该值通过引用传递给名为 remove 的函数。但是，我编写的代码似乎不适用于通过引用传递的值......或者也许我没有正确初始化它。我收到"错误错误：_ret未在此范围内声明">

void DoublyLinkedList::remove(const string& s)
{
 if (current == nullptr){
   //return nullptr;
}
 Node *next_ = current->next;
 Node *prev_ = current->prev;
 //I THINK THIS IS WHERE I AM WRONG???
 _ret = Node(s);
 _ret = nullptr;
 //s _ret = nullptr;

 if (next_ != nullptr && prev_!=nullptr){
 current->prev->next = current->next;
 current->next->prev = current->prev;
 delete current->data;
 delete current;
 current = next_;
 _ret = current->data;
 }
 else if (next_ == nullptr && prev_==nullptr){
   this->head = this->tail = nullptr;
   delete current->data;
   delete current;
   current = nullptr;
   _ret = nullptr;
 }
 else if (next_ != nullptr && prev_ == nullptr){
   head = head->next;
   head->prev = nullptr;
   delete current->data;
   delete current;
   current = next_;
   _ret = current->data;
}
else if (next_ == nullptr && prev_ != nullptr){
   tail = tail->prev;
   tail->next = nullptr;
   delete current->data;
   delete current;
   current = nullptr;
   _ret = nullptr;
 }
}