`sig type key type 'a t val create : int -> 'a Hashtbl.S.t val clear : 'a Hashtbl.S.t -> unit val reset : 'a Hashtbl.S.t -> unit val copy : 'a Hashtbl.S.t -> 'a Hashtbl.S.t val add : 'a Hashtbl.S.t -> Hashtbl.S.key -> 'a -> unit val remove : 'a Hashtbl.S.t -> Hashtbl.S.key -> unit val find : 'a Hashtbl.S.t -> Hashtbl.S.key -> 'a val find_all : 'a Hashtbl.S.t -> Hashtbl.S.key -> 'a list val replace : 'a Hashtbl.S.t -> Hashtbl.S.key -> 'a -> unit val mem : 'a Hashtbl.S.t -> Hashtbl.S.key -> bool val iter : (Hashtbl.S.key -> 'a -> unit) -> 'a Hashtbl.S.t -> unit val filter_map_inplace : (Hashtbl.S.key -> 'a -> 'a option) -> 'a Hashtbl.S.t -> unit val fold : (Hashtbl.S.key -> 'a -> 'b -> 'b) -> 'a Hashtbl.S.t -> 'b -> 'b val length : 'a Hashtbl.S.t -> int val stats : 'a Hashtbl.S.t -> Hashtbl.statistics end`