anchor.diff:          | Br (p, m, s0, s1), Lf (k, y) ->
               if matchPrefix (k, p, m) then
                   if zeroBit (k, m) then
  -                    match PatriciaMap.Delete (k, s0) with
  +                    match PatriciaMap.Remove (k, s0) with
                       | Empty -> s1
                       | left ->
                           // OPTIMIZE : If left === s0 then return the map as-is instead of creating a new one.
                           Br (p, m, left, s1)
                   else
  -                    match PatriciaMap.Delete (k, s1) with
  +                    match PatriciaMap.Remove (k, s1) with
                       | Empty -> s0
                       | right ->
                           // OPTIMIZE : If right === s1 then return the map as-is instead of creating a new one.
  
positive.code:             
          | Br (_,_,_,_), Empty ->
              s
          | Lf (k, x), _ ->
              if PatriciaMap.ContainsKey (k, t) then Empty
              else s
          | Empty, _ ->
  
negative.code:         | Br (_,_,_,_), Empty ->
              Empty
              
          | Lf (k, _), _ ->
              // Here, we always use the value from the left tree, so as long as the
              // right tree contains a binding with the same key, we just return the left tree.
              if PatriciaMap.ContainsKey (k, t) then s
  