anchor.diff:              let f = (if isEnc then "Encode" else "Decode") + n
               let m = comp.GetClassInfo(providerType).Value.Methods.Keys |> Seq.find (fun m -> m.Value.MethodName = f)
               Call(Some x, NonGeneric providerType, NonGeneric m, args)
  +        let invokeId (comp: M.ICompilation) x = 
  +            let m = comp.GetClassInfo(providerType).Value.Methods.Keys |> Seq.find (fun m -> m.Value.MethodName = "Id")
  +            Call(Some x, NonGeneric providerType, NonGeneric m, [])
   
           type EncodeResult = Choice<Expression, string, unit>
   
  
positive.code:                 match comp.GetCustomTypeInfo t.TypeDefinition with
                  | M.EnumInfo _ -> ok ident
                  | M.FSharpRecordInfo fields ->
                      ((fun es ->
                          let es, tts = List.unzip es
                          let tn = 
                              match comp.GetClassInfo t.TypeDefinition |> Option.bind (fun cls -> cls.Address) with
                              | Some a -> GlobalAccess a
                              | _ -> Undefined
                          ok (call "Record" [tn; NewArray es])
                          ), fields)
                      ||> List.fold (fun k f es -> // f                        
                              if Option.isSome f.DateTimeFormat then
                                  warn (sprintf "Warning: This record field has a custom DateTime format: %s.%s. \
                                      Client-side JSON serialization does not support custom DateTime formatting. \
  
negative.code:                                                 e.Value.FullName = "Microsoft.FSharp.Core.FSharpOption`1" -> false
                                              | _ -> true
                                          )
                                          |> Seq.map (fun rf -> rf.JSName) |> Set.ofSeq
                                      | _ -> 
                                          match uci.Kind with 
                                          | M.NormalFSharpUnionCase fs ->
  