anchor.diff:  
   let contentType = "application/json; charset=utf-8"
   
  -let jsonWebPart fWebpart json = 
  +let json fWebpart json = 
     json
     |> Json.format
     |> fWebpart
  
positive.code:   ["msg", String msg]
    |> Map.ofList
    |> Object
    |> jsonWebPart fWebpart
  
  let badRequest msg = 
    error RequestErrors.BAD_REQUEST msg
  
negative.code: let internalError =
    error ServerErrors.INTERNAL_ERROR "something went wrong"
  
  let ok =
    json (Successful.OK)