open Localref;;

let prs s = print_string s; print_newline();;
let pri i = print_int i; print_newline();;
let pr s = print_string (s^": ");;


eval
  (fun memory ->
     let ref x = ref memory x in
       ref 0
         (fun p -> 
            pr "p"; pri (!p); 
            p := 3;
            pr "p"; pri (!p);
            backup p (fun () -> 
                 pr "p"; pri (!p);
                 p := 2;
                 pr "p"; pri (!p));
            pr "p"; pri (!p))
  )
;;

print_newline();; 
print_string "End of examples";;
print_newline();;