`sig
type key = T.t
type 'a t = 'a Hashtbl.Make(T).t
val create : int -> 'a t
val clear : 'a t -> unit
val reset : 'a t -> unit
val copy : 'a t -> 'a t
val add : 'a t -> key -> 'a -> unit
val remove : 'a t -> key -> unit
val find : 'a t -> key -> 'a
val find_opt : 'a t -> key -> 'a option
val find_all : 'a t -> key -> 'a list
val replace : 'a t -> key -> 'a -> unit
val mem : 'a t -> key -> bool
val iter : (key -> 'a -> unit) -> 'a t -> unit
val filter_map_inplace : (key -> 'a -> 'a option) -> 'a t -> unit
val fold : (key -> 'a -> 'b -> 'b) -> 'a t -> 'b -> 'b
val length : 'a t -> int
val stats : 'a t -> Hashtbl.statistics
val to_seq : 'a t -> (key * 'a) Seq.t
val to_seq_keys : 'a t -> key Seq.t
val to_seq_values : 'a t -> 'a Seq.t
val add_seq : 'a t -> (key * 'a) Seq.t -> unit
val replace_seq : 'a t -> (key * 'a) Seq.t -> unit
val of_seq : (key * 'a) Seq.t -> 'a t
val to_list : 'a t -> (T.t * 'a) list
val of_list : (T.t * 'a) list -> 'a t
val to_map : 'a t -> 'a Map.Make(T).t
val of_map : 'a Map.Make(T).t -> 'a t
val memoize : 'a t -> (key -> 'a) -> key -> 'a
val map : 'a t -> ('a -> 'b) -> 'b t
end`