    sig
      val fprintf :
        Pervasives.out_channel -> ('a, Pervasives.out_channel, unit) format -> 'a
      val printf : ('a, Pervasives.out_channel, unit) format -> 'a
      val eprintf : ('a, Pervasives.out_channel, unit) format -> 'a
      val sprintf : ('a, unit, string) format -> 'a
      val bprintf : Buffer.t -> ('a, Buffer.t, unit) format -> 'a
      val scan_format :
        string ->
        int ->
        (string -> int -> 'a) ->
        ('b -> 'c -> int -> 'a) -> ('d -> int -> 'a) -> 'a
    end