def _update_ipython_widget(self, value=None):
        """
        Update the progress bar to the given value (out of a total
        given to the constructor).

        This method is for use in the IPython notebook 2+.
        """

        # Create and display an empty progress bar widget,
        # if none exists.
        if not hasattr(self, '_widget'):
            self._widget = create_progress_widget()
            if in_ipython_frontend() and is_widgets_available():
                display(self._widget)
            self._widget.value = 0

        # Calculate percent completion, and update progress bar
        percent = (float(value)/self._total) * 100.0
        self._widget.value = percent
        self._widget.description =' ({0:>6s}%)'.format('{0:.2f}'.format(percent))
Update the progress bar to the given value (out of a total
        given to the constructor).

        This method is for use in the IPython notebook 2+.