Make.1-Ioval output_char : out_channel -> char -> unit Lwt.tval output_string : out_channel -> string -> unit Lwt.tval flush : out_channel -> unit Lwt.tval input_char : in_channel -> char Lwt.tval really_input : in_channel -> bytes -> int -> int -> unit Lwt.tval close_in : in_channel -> unit Lwt.tval open_connection : sockaddr -> (in_channel * out_channel) Lwt.t