val create : unit -> ('k, 'd) t
val get_key : ('k, 'd) t -> 'k option
val get_key_copy : ('k, 'd) t -> 'k option
val set_key : ('k, 'd) t -> 'k -> unit
val unset_key : ('k, 'd) t -> unit
val check_key : ('k, 'd) t -> bool
val blit_key : ('k, 'a) t -> ('k, 'b) t -> unit
val get_data : ('k, 'd) t -> 'd option
val get_data_copy : ('k, 'd) t -> 'd option
val set_data : ('k, 'd) t -> 'd -> unit
val unset_data : ('k, 'd) t -> unit
val check_data : ('k, 'd) t -> bool
val blit_data : ('a, 'd) t -> ('b, 'd) t -> unit
val make : 'k -> 'd -> ('k, 'd) t
val query : ('k, 'd) t -> 'k -> 'd option