sig
type t = Zones.Data.t Zones.IH.t
val create : int -> 'a Zones.IH.t
val find : 'a Zones.IH.t -> int -> 'a
val add : Locations.Zone.t Zones.IH.t -> int -> Locations.Zone.t -> unit
val pretty : Format.formatter -> Locations.Zone.t Zones.IH.t -> unit
end