anchor.diff:      patched
       |> serialize
       |> OK
  -  | None -> NOT_FOUND request.url.AbsoluteUri
  +  | None -> request |> urlWithHost |> NOT_FOUND
   
   let post request = 
     let todo = 
  
positive.code:     |> propertyInfo.GetValue
      |> unbox
    
    match find request.url.AbsoluteUri with
    | Some todo ->
      store.Remove todo |> ignore
      let getPatchedProperty expr = getPatchedProperty expr patchedTodo todo
  
negative.code:   |> serialize
    |> OK
  
  let urlWithHost (request : HttpRequest) =
    let host = request.headers |> List.find (fst >> (=) "host") |> snd
    sprintf "%s://%s%s" request.url.Scheme host request.url.PathAndQuery
  
  let getTodo id =
    match find id with
    | Some todo -> serialize todo |> OK
  