val maci_bytes : key:Native.st -> ((Native.st -> unit) -> 'a) -> tval maci_string : key:string -> ((string -> unit) -> 'a) -> stringval mac_bytes : key:Native.st -> ?off:??? -> ?len:??? -> Native.st -> tval mac_string : key:string -> ?off:??? -> ?len:??? -> string -> stringval macv_bytes : key:Native.st -> Native.st list -> tval macv_string : key:string -> string list -> string