anchor.diff:      let createApp appState =
           {
               AppState = appState
  +            Init = (fun _ -> ())
               JsCalls = []
               Node = None
               CurrentTree = None
  
positive.code:                         let tree = renderTree state.AppState.View post state.AppState.Model
                          let rootNode = renderer.CreateElement tree
                          startElem.appendChild(rootNode) |> ignore
                          return! loop {state with CurrentTree = Some tree; Node = Some rootNode}
                      | Some rootNode, Some currentTree ->
                          let! message = inbox.Receive()
  
negative.code:     type App<'TModel, 'TMessage> =
          {
              AppState: AppState<'TModel, 'TMessage>
              Init : ('TMessage -> unit) -> unit
              JsCalls: (unit -> unit) list
              Node: Node option
              CurrentTree: obj option
  