val maci_bytes : key:By.t -> ((By.t -> unit) -> 'a) -> stringval maci_string : key:string -> ((string -> unit) -> 'a) -> stringval mac_bytes : key:By.t -> ?off:??? -> ?len:??? -> By.t -> tval mac_string : key:string -> ?off:??? -> ?len:??? -> string -> stringval macv_bytes : key:By.t -> By.t list -> stringval macv_string : key:string -> string list -> string