anchor.diff:          let tr = fst (encNode (treeF.GetValue x))
           EncodedObject [ "tree", tr ] |> i.AddTag t
   
  +[<MethodImpl(MethodImplOptions.NoInlining)>]
  +let makeMap<'T> (dV: Value -> obj) =
  +    let dV x = dV x // Force the method to return an FSharpFunc instead of taking 2 args
  +    fun (vs: list<string * Value>) ->
  +        Map.ofList<string, 'T>(
  +            vs |> List.map (fun (k, v) -> k, unbox (dV v))
  +        )
  +        |> box
  +
   let mapDecoder dD (i: FormatSettings) (t: System.Type) =
       let tg = t.GetGenericArguments()
       if tg.Length <> 2 then raise DecoderException
       let dK = dD tg.[0]
       let dV = dD tg.[1]
  +    if i.FlattenCollections && tg.[0] = typeof<string> then
  +        let x = makeMap dV // Prevents makeMap from being dead-code-eliminated
  +        let f =
  +            FastInvoke.Compile(
  +                thisModule.GetMethod("makeMap",
  +                    flags ||| System.Reflection.BindingFlags.Static
  +                ).MakeGenericMethod(tg.[1])
  +            ).Invoke1(dV)
  +            :?> (list<string * Value> -> obj)
  +        function
  +        | Object vs -> f vs
  +        | _ -> raise DecoderException
  +    else
       let tt = typedefof<System.Tuple<_,_>>.MakeGenericType(tg.[0], tg.[1])
       let cT = FSV.PreComputeTupleConstructor(tt)
       fun (x: Value) ->
  
positive.code: let listModule =
      typeof<Set<_>>.Assembly
          .GetType("Microsoft.FSharp.Collections.ListModule")
  
  let makeEmptySet (t: System.Type) =
      setModule
  
negative.code:         | Some v -> dec v
          | None -> raise DecoderException
  
  let opsModule =
      typeof<Set<_>>.Assembly
          .GetType("Microsoft.FSharp.Core.Operators")
  
  let setModule =
      typeof<Set<_>>.Assembly
          .GetType("Microsoft.FSharp.Collections.SetModule")
  
  let mapModule =
      typeof<Set<_>>.Assembly
          .GetType("Microsoft.FSharp.Collections.MapModule")
  
  let seqModule =
      typeof<Set<_>>.Assembly
          .GetType("Microsoft.FSharp.Collections.SeqModule")
  