include module type of struct include Stdlib.Unit end
val equal : t -> t -> bool
val compare : t -> t -> int
val to_string : t -> string
val unit_e : (unit, 'a) Stdlib.result
val unit_es : (unit, 'a) Stdlib.result Lwt.t
val catch : ?catch_only:(exn -> bool) -> (t -> t) -> t
val catch_f : ?catch_only:(exn -> bool) -> (t -> t) -> (exn -> t) -> t
val catch_s : ?catch_only:(exn -> bool) -> (unit -> unit Lwt.t) -> unit Lwt.t