`functor (H : Hashtbl.HashedType) -> sig type data = H.t type t val create : int -> t val clear : t -> unit val merge : t -> data -> data val add : t -> data -> unit val remove : t -> data -> unit val find : t -> data -> data val find_all : t -> data -> data list val mem : t -> data -> bool val iter : (data -> unit) -> t -> unit val fold : (data -> 'a -> 'a) -> t -> 'a -> 'a val count : t -> int val stats : t -> int * int * int * int * int * int end`