[이우석]

주석처리 된 곳을 구현하세요.

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module type PHONEBOOK =
sig
type t
type name = string
type number = string
exception Empty
val empty : t
val add : name * number -> t -> t
val del : name * number -> t -> t
val lookup : name -> t -> number list
val pprint : t -> unit
end

module PhoneBook : PHONEBOOK =
struct
type name = string
type number = string

module NumSet = Set.Make(struct type t = number let compare = compare end)
module Pb = Map.Make(struct type t = name let compare = compare end)

type t = NumSet.t Pb.t

exception Empty
let empty = Pb.empty
let add (name, num) t = (* Not Implemented *)
let del (name, num) t = (* Not Implemented *)
let lookup name t = (* Not Implemented *)
let pprint t =
let list_print lst = List.iter (fun x -> print_endline ("\t"^x)) lst in
Pb.iter (fun x y -> print_endline (x^" :: "); list_print (NumSet.elements (Pb.find x t))) t

end