module Base64:Base64 codec.sig
..end
8-bit characters are encoded into 6-bit ones using ASCII characters A-Z,
a-z, 0-9, and '+' , '/' (in that order).
exception Invalid_char
val str_encode : string -> string
val str_decode : string -> string
Invalid_char
if a
character in the input string is not a valid one.val encode : 'a IO.output -> 'a IO.output
val decode : IO.input -> IO.input