anchor.diff:  
   let render handler view viewState =
       let tree = renderSomething handler view
  -    {viewState with CurrentTree = tree}
  +    {viewState with NextTree = tree}
   
   let createRender selector handler view =
       let node = document.body.querySelector(selector) :?> HTMLElement
  
positive.code:     let mutable viewState = 
          {
              CurrentTree = tree
              Node = vdomNode
          }
      let render' handler view = 
          let viewState' = render handler view viewState
          let patches = diff viewState.CurrentTree viewState'.CurrentTree
          patch viewState.Node patches |> ignore
          viewState <- viewState'
      render'
  
negative.code:     let elem = h(tag, toAttrs attributes, List.toArray children)
      elem
  
  type RenderState = 
      | NoRequest
      | PendingRequest
      | ExtraRequest
  
  type ViewState<'TMessage> = 
      {
          CurrentTree: obj
          NextTree: obj
          Node: Node 
          RenderState: RenderState
      }
  
  let rec renderSomething handler node = 
  