    sig
      type t
      val create : int -> Buffer.t
      val contents : Buffer.t -> string
      val length : Buffer.t -> int
      val clear : Buffer.t -> unit
      val reset : Buffer.t -> unit
      val add_char : Buffer.t -> char -> unit
      val add_string : Buffer.t -> string -> unit
      val add_substring : Buffer.t -> string -> int -> int -> unit
      val add_buffer : Buffer.t -> Buffer.t -> unit
      val add_channel : Buffer.t -> Pervasives.in_channel -> int -> unit
      val output_buffer : Pervasives.out_channel -> Buffer.t -> unit
    end