anchor.diff:      member __.ToSeq () =
           trie.ToSeq ()
   
  -    (* OPTIMIZE : The methods below should be replaced with optimized implementations where possible. *)
  -
       //
       member this.Choose (chooser : int -> 'T -> 'U option) : IntMap<'U> =
           let chooser = FSharpFunc<_,_,_>.Adapt chooser
  
positive.code:                 map1,
                  map2.Add (key, value)), (IntMap.Empty, IntMap.Empty))
  
      // TODO
      // union
  
  //
  and [<Sealed>]
  
negative.code: [<Sealed>]
  [<DebuggerTypeProxy(typedefof<IntMapDebuggerProxy<int>>)>]
  [<DebuggerDisplay("Count = {Count}")>]
  type IntMap< [<EqualityConditionalOn>] 'T> private (trie : PatriciaMap<'T>) =
      /// The empty IntMap.
      static member Empty
          with get () : IntMap<'T> =
  