let squel ~f_init ~f_end ~f_key ~f_mouse ~f_except = 
        f_init () ;
        try 
        while true do 
                try 
                        let s = Graphics.wait_next_event  [Graphics.Button_down; Graphics.Key_pressed] 
                        in 
                        if s.Graphics.keypressed then f_key s.Graphics.key
                        else 
                         if s.Graphics.button 
                         then f_mouse s.Graphics.mouse_x s.Graphics.mouse_y
                with 
                | Fin -> raise Fin
                |  e  -> f_except e
        done
        with 
        Fin  -> f_end ()