sig
type t
val empty : t
val add : t -> t -> t
val sub : t -> t -> t
val opp : t -> t
val compare : t -> t -> int
val length : Time.t -> int
val mul : Time.t -> Time.t -> Time.t
val div : Time.t -> Time.t -> Time.t
val make : int -> int -> int -> Time.t
val lmake : ?hour:int -> ?minute:int -> ?second:int -> unit -> Time.t
val hour : int -> Time.t
val minute : int -> Time.t
val second : int -> Time.t
val to_seconds : Time.t -> int
val to_minutes : Time.t -> float
val to_hours : Time.t -> float
end