type in_channel = Gzip.in_channel
val open_in : string -> in_channel
val open_in_chan : in_channel -> in_channel
val input_char : in_channel -> char
val input_byte : in_channel -> int
val input : in_channel -> string -> int -> int -> int
val really_input : in_channel -> string -> int -> int -> unit
val close_in : in_channel -> unit
val dispose : in_channel -> unit
type out_channel = Gzip.out_channel
val open_out : ?level:int -> string -> out_channel
val open_out_chan : ?level:int -> out_channel -> out_channel
val output_char : out_channel -> char -> unit
val output_byte : out_channel -> int -> unit
val output : out_channel -> string -> int -> int -> unit
val close_out : out_channel -> unit
val flush : out_channel -> unit
exception Error of string