anchor.diff:                      "/active" ==> nowShowing ACTIVE_TODOS
                       "/completed" ==> nowShowing COMPLETED_TODOS
               ])
  -        // We haven't defined any interface for the router object but we can
  -        // can still dynamically access its properties with the `?` operator. 
           router?init("/")
   
       member this.handleChange (ev: React.SyntheticEvent) =
  
positive.code:    is to take advantage of the full power of [React](https://facebook.github.io/react/) in Fable apps.
     You can also compare the [F# source code](https://github.com/fable-compiler/Fable/blob/master/samples/browser/react-todomvc/react-todomvc.fsx)
     with the [original JS implementation](https://github.com/tastejs/todomvc/tree/gh-pages/examples/react)
     to see the advantages of Fable programming. And remember [Fable is also compatible with React Native](http://www.navision-blog.de/blog/2016/08/06/fable-react-native/) for mobile development!
  *)
  
  (**
  
negative.code:                 OnKeyDown this.handleKeyDown
              ] []
          ]
  
  (**
  The next view is `TodoFooter`. This component just presents some buttons below
  the Todo list to filter by or change the `completed` property of the Todos.
  
  Same as `TodoItem`, notice the component subscribes to some events (like `OnClick`)
  but instead of containing the logic to react to the event it just runs a callback
  received from its parent through the `props` object. Remember the state of React
  components cannot be directly updated, so this is a way to transmit the event to
  the parent and let it re-render the subtree if necessary. 
  *)
  
  type TodoFooterProps =
      abstract count: int
  