def METHOD_NAME(self, event):
    level = self._get_backlight_level()
    button = event["button"]
    if button == self.button_up:
        delta = self.brightness_delta if level >= self.low_tune_threshold else 1
        level += delta
        if level > 100:
            level = 100
        self._set_backlight_level(level)
    elif button == self.button_down:
        delta = self.brightness_delta if level > self.low_tune_threshold else 1
        level -= delta
        if level < self.brightness_minimal:
            level = self.brightness_minimal
        self._set_backlight_level(level)