diff --git a/Labs/06.rkt b/Labs/06.rkt
index bae09ed..81275b9 100644
--- a/Labs/06.rkt
+++ b/Labs/06.rkt
@@ -3,11 +3,58 @@
   [mt]
   [node (b : (Boxof (Optionof Number))) (l : BoxTree) (r : BoxTree)])
 
+#;(define (unify-trees! t1 t2)
+  (cond
+    [(and (mt? t1) (mt? t2)) (void)]
+    [(or (mt? t1) (mt? t2)) (error 'unify-trees! "shape mismatch")]
+    [else
+     (let* ([t1-l (node-l t1)]
+            [t1-r (node-r t1)]
+            [t2-l (node-l t2)]
+            [t2-r (node-r t2)])
+       (begin
+         (type-case BoxTree t1-l
+           [(node b l r) (type-case (Optionof Number) (unbox b)
+                           [(some b) (set-box! (node-b t1-r) (unbox (node-b t2-r)))]
+                           [(none) (set-box! (node-b t1-l) (unbox (node-b t2-l)))])]
+           [else (void)])
+         (type-case BoxTree t2-l
+           [(node b l r) (type-case (Optionof Number) (unbox b)
+                           [(some b) (set-box! (node-b t2-r) (unbox (node-b t1-r)))]
+                           [(none) (set-box! (node-b t2-l) (unbox (node-b t1-l)))])]
+           [else (unify-trees! )])))]))
+
+#;(define (unify-trees! t1 t2)
+  (cond
+    [(and (mt? t1) (mt? t2)) (void)]
+    [(or (mt? t1) (mt? t2)) (error 'unify-trees! "shape mismatch")]
+    [else
+     (let* ([t1-l (node-l t1)]
+            [t1-r (node-r t1)]
+            [t2-l (node-l t2)]
+            [t2-r (node-r t2)])
+       (begin
+         (type-case BoxTree t1-l
+           [(node b l r) (type-case (Optionof Number) (unbox b)
+                           [(some b) (set-box! (node-b t1-r) (unbox (node-b t2-r)))]
+                           [(none) (set-box! (node-b t1-l) (unbox (node-b t2-l)))])]
+           [else (void)])
+         (type-case BoxTree t2-l
+           [(node b l r) (type-case (Optionof Number) (unbox b)
+                           [(some b) (set-box! (node-b t2-r) (unbox (node-b t1-r)))]
+                           [(none) (set-box! (node-b t2-l) (unbox (node-b t1-l)))])]
+           [else (void)])
+         (unify-trees! t1-l t1-r)
+         (unify-trees! t2-l t2-r)))]))
+
 (define (unify-trees! t1 t2)
   (cond
     [(and (mt? t1) (mt? t2)) (void)]
     [(or (mt? t1) (mt? t2)) (error 'unify-trees! "shape mismatch")]
-    [(
+    [else
+     
+
+
 
 (module+ test
   ;; Same shape, one "variable" in each