anchor.diff:          let info = makeCallInfo None args [t; Boolean]
           let value = makeCall r Unit info value
           Delegate([v], value, None)
  -    Helper.LibCall(com, "types", "FSharpRef", t, [getter; setter], isJsConstructor=true)
  +    Helper.LibCall(com, "types", "FSharpRef", t, [getter; setter], isPyConstructor=true)
   
   // let turnLastArgIntoRef com ctx args =
   //     let args, defValue = List.splitLast args
  
positive.code:     let setter =
          let v = makeUniqueIdent ctx t "v"
          Delegate([v], Set(value, ValueSet, t, IdentExpr v, None), None)
      Helper.LibCall(com, "types", "FSharpRef", t, [getter; setter], isJsConstructor=true)
  
  let makeRefFromMutableField com ctx r t callee key =
      let getter =
  
negative.code:         // makeComparer com ctx key
          makeEqualityComparer com ctx key
          |> makeDictionaryWithComparer com r t sourceSeq
      | _ -> Helper.GlobalCall("dict", t, [sourceSeq], isPyConstructor=true, ?loc=r)
  
  let makeHashSetWithComparer com r t sourceSeq comparer =
      Helper.LibCall(com, "mutable_set", "HashSet", t, [sourceSeq; comparer], isPyConstructor=true, ?loc=r)
  
  let makeHashSet (com: ICompiler) ctx r t sourceSeq =
      match t with
  