sig
type key
type 'a t
val create : int -> 'a t
val iter : (key -> 'a -> unit) -> 'a t -> unit
val fold : (key -> 'a -> 'b -> 'b) -> 'a t -> 'b -> 'b
val add : 'a t -> key -> 'a -> unit
val replace : 'a t -> key -> 'a -> unit
val length : 'a t -> int
val find_all : 'a t -> key -> 'a list
val clear : 'a t -> unit
val find : 'a t -> key -> 'a
val remove : 'a t -> key -> unit
val mem : 'a t -> key -> bool
end