I am a noob and do not understand this error

[Jacek_Podkanski]

Found this

Would somebody help me to run this code?

let rec tic () = let () = print_endline "tic" in let* () = Lwt_unix.sleep 1.0 in tic () let _ = Lwt_main.run tic I get the following error: let _ = Lwt_main.run tic ^^^ Error: This expression has type unit -> 'a Lwt.t but an expression was expected of type 'b Lwt.t Hint: Did you forget to provide `()' as argument?

and got the clue;

I needed to add the () as an argument

let canvas = drawing_area_new () in