anchor.diff:              None
           | Lf k ->
               picker (int k)
  -        | Br (_,_,_,_) as t ->
  +        | Br (_,_,_,_) ->
               /// The stack of trie nodes pending traversal.
               let stack = Stack (defaultTraversalStackSize)
   
               // Add the initial tree to the stack.
  -            stack.Push t
  +            stack.Push set
   
               /// Loop until we find a key/value that matches the picker,
               /// or until we've processed the entire tree.
  
positive.code:         | Empty -> ()
          | Lf k ->
              action (int k)
          | Br (_,_,_,_) as t ->
              /// The stack of trie nodes pending traversal.
              let stack = Stack (defaultTraversalStackSize)
  
              // Add the initial tree to the stack.
              stack.Push t
  
              // Loop until we've processed the entire tree.
              while stack.Count <> 0 do
  
negative.code:             state
          | Lf k ->
              folder (int k) state
          | Br (_,_,_,_) ->
              let folder = FSharpFunc<_,_,_>.Adapt folder
  
              /// The stack of trie nodes pending traversal.
              let stack = Stack (defaultTraversalStackSize)
  
              // Add the initial tree to the stack.
              stack.Push set
  
              /// Loop until we've processed the entire tree.
              let mutable state = state
  