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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def __update_keyboard(self, milliseconds):
 """ Use the keyboard to control selection of the buttons. """

        if Ragnarok.get_world().Keyboard.is_clicked(self.move_up_button):
            self.move_up()
        elif Ragnarok.get_world().Keyboard.is_clicked(self.move_down_button):
            self.move_down()
        elif Ragnarok.get_world().Keyboard.is_clicked(self.select_button):
            self.gui_buttons[self.current_index].clicked_action()

        for button in self.gui_buttons:
            button.update(milliseconds)