anchor.diff:  let runinit file =
       let byte = File.ReadAllBytes(file)
       let str = System.Text.ASCIIEncoding.Default.GetString byte
  -    printf "%s" str
  +    match run json str with
  +    | Success(result, _, _)   -> printfn "Success: %A" result
  +    | Failure(errorMsg, _, _) -> printfn "Failure: %s" errorMsg
       0
   
   let runload file =
  
positive.code:     | [| "--init" ; file |] -> runinit file
      | [| "--load" ; file |] -> runload file
      | [| "--play" |]        -> runplay
      | _                     -> 1 (* Error *)
  
negative.code: (* Datatype *)
  type Album = { Name: string; Year: int }
  type Song  = { Artist: string; Song: string; TimeInSec: int; Album: Album }
  
  (* Parse JSON *)
  type Json = JString of string
  