# Module Tbl

    module Tbl: sig .. end

    type ('a, 'b) t

    val empty : ('a, 'b) t

    val add : 'a -> 'b -> ('a, 'b) t -> ('a, 'b) t

    val find : 'a -> ('a, 'b) t -> 'b

    val mem : 'a -> ('a, 'b) t -> bool

    val remove : 'a -> ('a, 'b) t -> ('a, 'b) t

    val iter : ('a -> 'b -> unit) -> ('a, 'b) t -> unit

    val map : ('a -> 'b -> 'c) -> ('a, 'b) t -> ('a, 'c) t

    val fold : ('a -> 'b -> 'c -> 'c) -> ('a, 'b) t -> 'c -> 'c

    val print : (Format.formatter -> 'a -> unit) ->
           (Format.formatter -> 'b -> unit) ->
           Format.formatter -> ('a, 'b) t -> unit