diff --git a/src/listhead.rs b/src/listhead.rs
index b4c3dcf..f63d959 100644
--- a/src/listhead.rs
+++ b/src/listhead.rs
@@ -29,11 +29,58 @@ impl<T> ListHead<T> {
         self.prev.upgrade().unwrap().borrow_mut().next = self.next.clone();
     }
 
-    pub fn add_tail(&mut self, pnew: &mut ListHead<T>) {
-        let prev = &mut self.prev;
-        unsafe {
-            let next = Weak::from_raw(self);
-        }
+    pub fn add_tail(head: &mut Rc::<RefCell::<ListHead<T>>>,
+                    pnew: &mut Rc::<RefCell::<ListHead<T>>>) {
+        let prev = &mut head.borrow_mut().prev;
+        let next = Rc::downgrade(head);
+
+        next.upgrade().unwrap().borrow_mut().prev = Rc::downgrade(pnew);
+        pnew.borrow_mut().next = next;
+        pnew.borrow_mut().prev = prev.clone();
+        prev.upgrade().unwrap().borrow_mut().next = Rc::downgrade(pnew);
     }
 
 }
+/*
+pub struct ListHead<T> {
+    prev: Weak::<ListHead<T>>,
+    next: Weak::<ListHead<T>>,
+    data: Weak::<RefCell::<T>>,
+}
+
+impl<T> ListHead<T> {
+
+    pub fn new() -> RefCell::<Rc::<ListHead<T>>> {
+        let mut this = Rc::new(ListHead{
+            prev: Weak::<ListHead<T>>::new(),
+            next: Weak::<ListHead<T>>::new(),
+            data: Weak::<RefCell::<T>>::new(),
+        });
+        let p = RefCell::new(this);
+        //this.prev = Rc::downgrade(&this).clone();
+        //this.prev = Weak::<ListHead<T>>::new();
+        //this.next = Rc::downgrade(&this);
+        //p.borrow_mut().prev = Rc::downgrade(&p.borrow());
+        p.borrow_mut().prev = Weak::<ListHead<T>>::new();
+        return p;
+    }
+    /*
+    pub fn data(&self) -> &Weak::<RefCell::<T>> {
+        return &self.data;
+    }
+
+    pub fn del(&mut self) {
+        self.next.upgrade().unwrap().borrow_mut().prev = self.prev.clone();
+        self.prev.upgrade().unwrap().borrow_mut().next = self.next.clone();
+    }
+
+    pub fn add_tail(&mut self, pnew: &mut ListHead<T>) {
+        let prev = &mut self.prev;
+        unsafe {
+            let next = Weak::from_raw(&self);
+            //next.upgrade().unwrap().borrow_mut().prev = Weak::from_raw(pnew);
+        }
+    }
+    */
+}
+*/