Parameter Async.1-ML

type async_chan
type condition
type watch_id
val add_watch : callback:( condition list -> bool ) -> async_chan -> watch_id
val remove_watch : watch_id -> unit
val read_all : async_chan -> string
val async_chan_of_file : Unix.file_descr -> async_chan
val async_chan_of_socket : Unix.file_descr -> async_chan