`sig external length : string -> int = "%string_length" external get : string -> int -> char = "%string_safe_get" external set : bytes -> int -> char -> unit = "%string_safe_set" external create : int -> bytes = "caml_create_string" val make : int -> char -> string val init : int -> (int -> char) -> string val copy : string -> string val sub : string -> int -> int -> string val fill : bytes -> int -> int -> char -> unit val blit : string -> int -> bytes -> int -> int -> unit val concat : string -> string list -> string val iter : (char -> unit) -> string -> unit val iteri : (int -> char -> unit) -> string -> unit val map : (char -> char) -> string -> string val mapi : (int -> char -> char) -> string -> string val trim : string -> string val escaped : string -> string val index : string -> char -> int val rindex : string -> char -> int val index_from : string -> int -> char -> int val rindex_from : string -> int -> char -> int val contains : string -> char -> bool val contains_from : string -> int -> char -> bool val rcontains_from : string -> int -> char -> bool val uppercase : string -> string val lowercase : string -> string val capitalize : string -> string val uncapitalize : string -> string val uppercase_ascii : string -> string val lowercase_ascii : string -> string val capitalize_ascii : string -> string val uncapitalize_ascii : string -> string type t = string val compare : String.t -> String.t -> int val equal : String.t -> String.t -> bool external unsafe_get : string -> int -> char = "%string_unsafe_get" external unsafe_set : bytes -> int -> char -> unit = "%string_unsafe_set" external unsafe_blit : string -> int -> bytes -> int -> int -> unit = "caml_blit_string" [@@noalloc] external unsafe_fill : bytes -> int -> int -> char -> unit = "caml_fill_string" [@@noalloc] end`