anchor.diff:    open Fable.Core.JsInterop
   
     let onInput x = onEvent "oninput" (fun e -> x (unbox e?target?value))
  -
  -type Operator =
  -  | Sum
  -  | Sub
  -  | Mul
  -  | Unknown
  -
  -type Model = 
  -  { Operator: Operator
  -    NumberA: int
  -    NumberB: int
  -  }
  -
  -  static member Initial =
  -    {
  -      Operator = Unknown
  -      NumberA = 0
  -      NumberB = 0
  -    }
  -
  -type Page =
  -  | Index
  -  | Sum of int * int
  -  | Sub of int * int
  -  | Mul of int * int
   
   type Actions =
     | NavigateTo of Page
  
positive.code: 
  let routerF m = router.Route m.Message
  
  // Using createSimpleApp instead of createApp since our
  // update function doesn't generate any actions. See
  // some of the other more advanced examples for how to
  // use createApp. In addition to the application functions
  // we also need to specify which renderer to use.
  createSimpleApp Model.Initial view update Virtualdom.createRender
  |> withStartNodeSelector "#sample"
  |> withProducer (routeProducer locationHandler router)
  |> withSubscriber (routeSubscriber locationHandler routerF)
  |> start
negative.code: open Fable.Arch.Html
  open Fable.Arch.RouteParser.Parsing
  open Fable.Arch.RouteParser.RouteParser
  open Fable.Core.JsInterop
  open Fable.Import.Browser
  open System.Text.RegularExpressions
  
  