+let stack = ref [];;
+
+let h2l h =
+ UriManager.UriHashtbl.fold
+ (fun k v acc -> (k,v) :: acc) h []
+;;
+
+let push () =
+ stack := (CoercDb.dump (), h2l coercion_hashtbl) :: !stack;
+ remove_all_coercions ()
+;;
+
+let pop () =
+ match !stack with
+ | [] -> raise (Failure "Unable to POP from librarySync.ml")
+ | (db,h) :: tl ->
+ stack := tl;
+ remove_all_coercions ();
+ CoercDb.restore db;
+ List.iter (fun (k,v) -> UriManager.UriHashtbl.add coercion_hashtbl k v)
+ h
+;;
+