如何通过依赖倒置原则解耦按钮与灯？匹配DIP文档图6实现

根据DIP文档中的图5，我编写了如下代码，请问如何修改以符合该文档的图6？

class Lamp:
    def __init__(self):
        self.state = "off"
    def turn_on(self):
        self.state = "on"
    def turn_off(self):
        self.state = "off"

class Button:
    def __init__(self, lamp):
        self.lamp = lamp
        self.state = "off"
        self.lamp.state = "off" 
    def on(self):
        self.state = "on"
        self.lamp.turn_on()
    def off(self):
        self.state = "off"
        self.lamp.turn_off()

lamp = Lamp()
button = Button(lamp)
assert lamp.state == "off"
button.on()
assert lamp.state == "on"

我考虑使用桥接模式（Bridge Pattern），但不确定如何编写实现。我尝试了以下代码，尽管断言运行正常，但仍感觉存在问题：

from abc import ABC, abstractmethod

class AbstractButton(ABC):
    def __init__(self, button_client):
        self.button_client = button_client
    @abstractmethod
    def on(self):
        pass
    @abstractmethod
    def off(self):
        pass

class Button(AbstractButton):
    def on(self):
        self.button_client.on()
    def off(self):
        self.button_client.off()

class ButtonClient(ABC):
    @abstractmethod
    def on(self):
        pass
    @abstractmethod
    def off(self):
        pass

class Lamp(ButtonClient):
    def __init__(self):
        self.state = "off"
    def on(self):
        self.state = "on"
    def off(self):
        self.state = "off"


lamp = Lamp()
button = Button(lamp)
assert lamp.state == "off"
button.on()
assert lamp.state == "on"
button.off()
assert lamp.state == "off"

现在受Python协议及某Stack Overflow问题启发，我编写了如下更简洁的代码，实现了包含可开关（Switchable）灯设备的按钮，状态仅在灯设备中存储，且两者均可被控制，但请问这段代码是否实现了解耦？

class Switchable:
    def __init__(self, device):
        self.device = device
        self.device.state = 'off'
    def turn_on(self):
        self.device.state = 'on'
    def turn_off(self):
        self.device.state = 'off'


class Lamp(Switchable):
    def __init__(self):
       super().__init__(self) 
    def __str__(self):
        return f"Lamp {self.state}"

lamp = Lamp()
button = Switchable(lamp)
assert str(lamp) == "Lamp off"
button.turn_on()
assert str(lamp) == "Lamp on"
button.turn_off()
assert str(lamp) == "Lamp off"
lamp.turn_on()
assert str(lamp) == "Lamp on"
lamp.turn_off()
assert str(lamp) == "Lamp off"
assert button.device.state == "off"

内容的提问来源于stack exchange，提问作者progmatico