`functor (H : HashedType) -> sig type key = H.t and 'a 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:key -> data:'a -> unit val remove : 'a t -> key -> unit val find : 'a t -> key -> 'a val find_all : 'a t -> key -> 'a list val replace : 'a t -> key:key -> data:'a -> unit val mem : 'a t -> key -> bool val iter : f:(key:key -> data:'a -> unit) -> 'a t -> unit val filter_map_inplace : f:(key:key -> data:'a -> 'a option) -> 'a t -> unit val fold : f:(key:key -> data:'a -> 'b -> 'b) -> 'a t -> init:'b -> 'b val length : 'a t -> int val stats : 'a t -> statistics end`