def _update(self): 
        """ Update the label with elapsed time. """
        self._elapsedtime = time.time() - self._start
        self._setTime(self._elapsedtime)
        self._timer = self.after(50, self._update)
 Update the label with elapsed time. 
recipes/Python/578666_Stopwatch_with_laps_in_Tkinter/recipe-578666.py