def prev_month(self):
        """Updated calendar to show the previous week."""
        if self._selection_is_visible: self._clear_selection()
        
        date = self.datetime(self._year, self._month, 1) - self.timedelta(days=1)
        self._build_calendar(date.year, date.month) # reconstuct calendar
Updated calendar to show the previous week.
recipes/Python/580725_Tkinter_Datepicker_like_jQuery_UI/recipe-580725.py