anchor.diff:          this.Window.StockPricesChart.Series.Add series
       
       override this.EventStreams = 
  -        let buttonClicks = 
  -            [
  +        [ 
  +            yield! [
                   this.Window.Calculate, Calculate
                   this.Window.Clear, Clear
                   this.Window.CelsiusToFahrenheit, CelsiusToFahrenheit
  
positive.code:                 this.Window.AddStock, AddStockToPriceChart
              ]
              |> List.map(fun(button, value) -> button.Click |> Observable.mapTo value)
  
          buttonClicks @ 
          [ 
              this.Window.X.PreviewTextInput 
                  |> Observable.merge this.Window.Y.PreviewTextInput
                  |> Observable.map (fun x -> XorYChanging(x.Text, fun() -> x.Handled <- true))
  
              this.Window.Y.TextChanged |> Observable.map(fun _ -> YChanged(this.Window.Y.Text))
          ] 
  
      override this.SetBindings model = 
          Binding.FromExpression 
              <@ 
                  this.Window.Op.ItemsSource <- model.AvailableOperations 
                  this.Window.Op.SelectedItem <- model.SelectedOperation
                  this.Window.X.Text <- string model.X
                  this.Window.Y.Text <- string model.Y 
                  this.Window.Result.Text <- string model.Result 
  
negative.code:     | Hex1
      | Hex2
      | AddStockToPriceChart
      | YChanged of string
  
  type SampleView() as this =
  