let blit_string_of_int_2_digits =
let tbl = Array.init 100 ~f:(fun i -> Printf.sprintf "%02d" i) in
fun s ~pos i ->
if i >= 100 || i < 0 then
invalid_argf
"Time.string_of_int_2_digits: argument must be (0, 99) %d" i ();
String.blit ~src:tbl.(i) ~dst:s ~src_pos:0 ~dst_pos:pos ~len:2