anchor.diff:      /// No exception is thrown if the set doesn't contain the specified element.
       let rec remove value (tree : CharDiet) : CharDiet =
           // Preconditions
  -        assert (dietInvariant tree)
  -        assert (intervalsDisjoint tree)
  +        //assert (dietInvariant tree)
  +        //assert (intervalsDisjoint tree)
   
           match tree with
           | Empty ->
  
positive.code:         | Node (l, r, _, _) ->
              let root, l' = AvlTree.DeleteMax l
              AvlTree.mkt_bal_r (root, l', r)
  
      /// Removes the minimum (least) value from a AvlTree,
      /// returning the value along with the updated tree.
      /// No exception is thrown if the tree is empty.
      static member TryDeleteMin (tree : AvlTree<'T>) =
          // Preconditions
          assert (AvlTree.AvlInvariant tree)
  
          match tree with
          | Empty ->
              None, tree
          | Node (Empty, r, n, _) ->
              Some n, r
          | tree ->
              let n', l' = AvlTree.DeleteMin tree
              Some n', l'
  
      /// Removes the maximum (greatest) value from a AvlTree,
      /// returning the value along with the updated tree.
      /// No exception is thrown if the tree is empty.
      static member TryDeleteMax (tree : AvlTree<'T>) =
          // Preconditions
          assert (AvlTree.AvlInvariant tree)
  
          match tree with
          | Empty ->
              None, tree
          | Node (l, Empty, n, _) ->
              Some n, l
          | tree ->
              let n', r' = AvlTree.DeleteMax tree
              Some n', r'
  
      /// Removes the specified value from the tree.
      /// If the tree doesn't contain the value, no exception is thrown;
  
negative.code: 
      /// Determines if the intervals in a DIET are disjoint.
      let intervalsDisjoint (tree : CharDiet) : bool =
          //fst <| intervalsDisjointImpl tree Set.empty
          true
          
      /// Determines if a DIET is correctly formed.
      let rec dietInvariant (tree : CharDiet) =
  