`sig
type base = string
type t
val base : t -> base
val pos : t -> int
val length : t -> int
val create : ?pos:int -> ?len:int -> base -> t
val blit_to_string : t -> dst:string -> dst_pos:int -> unit
val blit_to_bigstring : t -> dst:Bigstring.t -> dst_pos:int -> unit
val blit_from_string : t -> src:string -> src_pos:int -> len:int -> unit
val blit_from_bigstring :
t -> src:Bigstring.t -> src_pos:int -> len:int -> unit
val concat : t list -> t
val concat_string : t list -> string
val concat_bigstring : t list -> Bigstring.t
val of_bigstring : Bigstring.t -> t
val of_string : string -> t
val to_bigstring : t -> Bigstring.t
val to_string : t -> string
val drop_prefix : t -> int -> t
val drop_suffix : t -> int -> t
val prefix : t -> int -> t
val suffix : t -> int -> t
end`