如何创建python kivy标签，该标签的颜色存储在一个变量中，其他kivy小部件类可以访问该变量并在运行时进行更新

pip install kivy

from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.boxlayout import BoxLayout
from kivy.properties import StringProperty

class ColorLabel(Label):
    color = StringProperty()  # 定义一个String类型的属性color

    def __init__(self, **kwargs):
        super(ColorLabel, self).__init__(**kwargs)
        self.text = "Hello, Kivy!"  # 标签的默认文本

    def on_color(self, instance, value):
        self.color = value  # 更新颜色变量时，自动调用该方法更新标签颜色
        self.canvas.before.clear()
        with self.canvas.before:
            self.canvas.before.add(Color(rgba=self.color))
            self.canvas.before.add(Rectangle(size=self.size, pos=self.pos))

class MyLayout(BoxLayout):
    def __init__(self, **kwargs):
        super(MyLayout, self).__init__(**kwargs)
        self.orientation = 'vertical'
        self.label = ColorLabel()
        self.add_widget(self.label)

        button = Button(text="Change Color", on_press=self.change_color)
        self.add_widget(button)

    def change_color(self, instance):
        self.label.color = "#FF0000"  # 在点击按钮时更新颜色变量

class MyApp(App):
    def build(self):
        return MyLayout()

if __name__ == '__main__':
    MyApp().run()