`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 -> f:(int -> char) -> string
val copy : string -> string
val sub : string -> pos:int -> len:int -> string
val fill : bytes -> pos:int -> len:int -> char -> unit
val blit :
src:string -> src_pos:int -> dst:bytes -> dst_pos:int -> len:int -> unit
val concat : sep:string -> string list -> string
val iter : f:(char -> unit) -> string -> unit
val iteri : f:(int -> char -> unit) -> string -> unit
val map : f:(char -> char) -> string -> string
val mapi : f:(int -> char -> char) -> string -> string
val trim : string -> string
val escaped : string -> string
val index : string -> char -> int
val index_opt : string -> char -> int option
val rindex : string -> char -> int
val rindex_opt : string -> char -> int option
val index_from : string -> int -> char -> int
val index_from_opt : string -> int -> char -> int option
val rindex_from : string -> int -> char -> int
val rindex_from_opt : string -> int -> char -> int option
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 : StringLabels.t -> StringLabels.t -> int
val equal : StringLabels.t -> StringLabels.t -> bool
val split_on_char : sep:char -> string -> string list
val to_seq : StringLabels.t -> char Seq.t
val to_seqi : StringLabels.t -> (int * char) Seq.t
val of_seq : char Seq.t -> StringLabels.t
external unsafe_get : string -> int -> char = "%string_unsafe_get"
external unsafe_set : bytes -> int -> char -> unit = "%string_unsafe_set"
external unsafe_blit :
src:string -> src_pos:int -> dst:bytes -> dst_pos:int -> len:int -> unit
= "caml_blit_string" [@@noalloc]
external unsafe_fill : bytes -> pos:int -> len:int -> char -> unit
= "caml_fill_string" [@@noalloc]
end`