anchor.diff:              // Either (a) h1,h2 differ by at most 2 - no rebalance needed.
               //        (b) h1 too small, i.e. h1+2 < h2
               //        (c) h2 too small, i.e. h2+2 < h1
  -            if   h1+2u < h2 then
  +            if   h1+balanceTolerance < h2 then
                   // case: b, h1 too small
                   // push t1 into low side of t2, may increase height by 1 so rebalance
                   AvlTree.Rebalance (AvlTree.Balance (comparer, t1, t21, k), t22, k2)
  -            elif h2+2u < h1 then
  +            elif h2+balanceTolerance < h1 then
                   // case: c, h2 too small
                   // push t2 into high side of t1, may increase height by 1 so rebalance
                   AvlTree.Rebalance (t11, AvlTree.Balance (comparer, t12, t2, k), k1)
  
positive.code:             else
                  match left with
                  | Empty ->
                      Node (left, right, (value, y), h)
                  | _ ->
                      let (u, v), l = AvlTree.ExtractMax left
                      if succ v = value then
  
negative.code: module internal Constants =
      //
      let [<Literal>] defaultStackCapacity = 16
      //
      let [<Literal>] balanceTolerance = 2u   //1u
  
  
  (*  NOTE :  The core functions implementing the AVL tree algorithm were extracted into OCaml
  