Silent Teacher - a game to teach basics of programming

Show and Tell
2

Nice, but I got stuck on concatenating two strings, there seems to be a bug there.

On this task

let
    a = "xz"
    b = "vcl"
in
    a ++ b

I input xzvcl but I get a flashing message showing the right answear:

let
    a = "xz"
    b = "vcl"
in
    a ++ b
= "xzvcl"

Even when I copy / paste that right answer it does not work.

I found the problem here, toString (string1 ++ string2) will return "xzvcl" in my case. If I typed in the surrounding quotes I could continue. Maybe that is intended?