anchor.diff:  
           override this.Register (screen, world) =
               let property = propertyFn screen
  -            let bindings = this.Binding (property.Get world, screen, world)
  +            let bindings = this.Bindings (property.Get world, screen, world)
               let world =
                   List.fold (fun world binding ->
                       match binding with
  
positive.code:             let model = property.Get world
              this.View (model, screen, world)
  
          abstract member Binding : 'model * Screen * World -> Binding<'message, 'command, Screen, World> list
          abstract member Message : 'message * 'model * Screen * World -> 'model * 'command list
          abstract member Command : 'command * 'model * Screen * World -> World
          abstract member View : 'model * Screen * World -> World
  
negative.code: 
          override this.Register (layer, world) =
              let property = propertyFn layer
              let bindings = this.Bindings (property.Get world, layer, world)
              let world =
                  List.fold (fun world binding ->
                      match binding with
  