anchor.diff:  
     [<Test>]
     let ``printfn`` () =
  -    <@ printfn "hoge" @> |> checkPrinted Out "hoge\r\n"
  -    <@ printfn "hoge%d" 1 @> |> checkPrinted Out "hoge1\r\n"
  -    <@ printfn "%s" "hoge" @> |> checkPrinted Out "hoge\r\n"
  +    <@ printfn "hoge" @> |> checkPrinted Out (appendNewLine "hoge")
  +    <@ printfn "hoge%d" 1 @> |> checkPrinted Out (appendNewLine "hoge1")
  +    <@ printfn "%s" "hoge" @> |> checkPrinted Out (appendNewLine "hoge")
   
     [<Test>]
     let ``failwith`` () = <@ failwith "hoge" @> |> checkExnMsg "hoge"
  
positive.code:     <@ eprintf "hoge%d" 1 @> |> checkPrinted Error "hoge1"
      <@ eprintf "%s" "hoge" @> |> checkPrinted Error "hoge"
  
    [<Test>]
    let ``eprintfn`` () =
      <@ eprintfn "hoge" @> |> checkPrinted Error "hoge\r\n"
      <@ eprintfn "hoge%d" 1 @> |> checkPrinted Error "hoge1\r\n"
      <@ eprintfn "%s" "hoge" @> |> checkPrinted Error "hoge\r\n"
      
    [<Test>]
    let ``fprintf`` () =
  
negative.code:     
    [<Test>]
    let ``fprintfn`` () =
      <@ let w = new RobWriter(System.Text.UTF8Encoding()) in fprintfn w "hoge"; w.Result @> |> check (appendNewLine "hoge")
      <@ let w = new RobWriter(System.Text.UTF8Encoding()) in fprintfn w "hoge%d" 1; w.Result @> |> check (appendNewLine "hoge1")
      <@ let w = new RobWriter(System.Text.UTF8Encoding()) in fprintfn w "%s" "hoge"; w.Result @> |> check (appendNewLine "hoge")
  
    [<Test>]
    let ``printf`` () =
  