========== .ml file ==========

let printf brick_verb verb message =
    Printf.ksprintf
      (fun s ->
       if brick_verb >= verb
       then Printf.printf "%s" s else ())
      message

========== .mli file ==========
val printf : int -> int -> (unit, unit, string, unit) format4 -> unit

========== another .ml file ==========
MyModule.printf 5 2 "Hello %s !" "myname"

==> Error :
This function has type
       int -> int -> (unit, unit, string, unit) format4 -> unit
       It is applied to too many arguments; maybe you forgot a `;'.