(* TEST *)

(* a simple test with mutually recursive functions *)
let test =
  let rec even = function
    | 0 -> true
    | n -> odd (n - 1)
  and odd = function
    | 0 -> false
    | n -> even (n - 1)
  in
  List.iter (fun i -> assert (even i <> odd i && even i = (i mod 2 = 0)))
    [0;1;2;3;4;5;6]