anchor.diff:      /// Creates an AVL tree whose root node holds the specified value
       /// and the specified left and right subtrees.
       let inline internal create value l (r : AvlTree<'T>) =
  -        Node (value, l, r, (max (ht l) (ht r)) + 1u)
  +        Node (value, l, r, (max (height l) (height r)) + 1u)
   
       let rec private mkt_bal_l n l (r : AvlTree<'T>) =
  -        if ht l = ht r + 2u then
  +        if height l = height r + 2u then
               match l with
               | Empty ->
                   failwith "mkt_bal_l"
               | Node (ln, ll, lr, _) ->
  -                if ht ll < ht lr then
  +                if height ll < height lr then
                       match lr with
                       | Empty ->
                           failwith "mkt_bal_l"
  
positive.code:     let empty : AvlTree<'T> = AvlTree.Empty
  
      /// Returns the height of an AVL tree's root node.
      let private ht (tree : AvlTree<'T>) =
          match tree with
          | Empty -> 0u
          | Node (_,_,_,h) -> h
  
negative.code:         | Node (_,_,_,_) -> false
  
      /// Implementation. Returns the height of an AVL tree.
      let rec private computeHeightRec (tree : AvlTree<'T>) cont =
          match tree with
          | Empty ->
              cont 0u
          | Node (_, l, r, _) ->
              computeHeightRec l <| fun height_l ->
              computeHeightRec r <| fun height_r ->
                  (max height_l height_r) + 1u
                  |> cont
  
      /// Returns the height of an AVL tree.
      let internal computeHeight (tree : AvlTree<'T>) =
          computeHeightRec tree id
  
      /// Determines if an AVL tree is correctly formed.
      /// It isn't necessary to call this at run-time, though it may be useful for asserting
  