sig
type 'a t
val create : unit -> 'a Type.Obj_tbl.t
val add : 'a Type.Obj_tbl.t -> 'b Type.ty -> 'b -> 'a -> unit
val find : 'a Type.Obj_tbl.t -> 'b Type.ty -> 'b -> 'a
val mem : 'a Type.Obj_tbl.t -> 'b Type.ty -> 'b -> bool
val iter : 'b Type.Obj_tbl.t -> ('a Type.ty -> 'a -> 'b -> unit) -> unit
end