`sig
type t = Buffer.t
val create : int -> t
val contents : t -> string
val sub : t -> int -> int -> string
val blit : t -> int -> string -> int -> int -> unit
val nth : t -> int -> char
val length : t -> int
val clear : t -> unit
val reset : t -> unit
val add_char : t -> char -> unit
val add_string : t -> string -> unit
val add_substring : t -> string -> int -> int -> unit
val add_substitute : t -> (string -> string) -> string -> unit
val add_buffer : t -> t -> unit
val add_input : t -> BatInnerIO.input -> int -> unit
val add_channel : t -> BatInnerIO.input -> int -> unit
val output_buffer : t -> string BatInnerIO.output
val enum : t -> char BatEnum.t
val of_enum : char BatEnum.t -> t
val print : 'a BatInnerIO.output -> t -> unit
end`