Cryptokit.transform

`object
method available_output : int
method finish : unit
method flush : unit
method get_byte : int
method get_char : char
method get_string : string
method get_substring : string * int * int
method input_block_size : int
method output_block_size : int
method put_byte : int -> unit
method put_char : char -> unit
method put_string : string -> unit
method put_substring : string -> int -> int -> unit
method wipe : unit
end`