如何在MDLabel中为文本使用变量？

from kivymd.uix.label import MDLabel

name = "John Doe"
label_text = f"Hello, {name}!"
label = MDLabel(text=label_text)

from kivy.properties import StringProperty
from kivymd.uix.label import MDLabel
from kivy.uix.boxlayout import BoxLayout

class MyBoxLayout(BoxLayout):
    name = StringProperty("John Doe")

    def __init__(self, **kwargs):
        super(MyBoxLayout, self).__init__(**kwargs)
        label = MDLabel()
        label.bind(text=self._on_name_change)
        self.add_widget(label)

    def _on_name_change(self, instance, value):
        instance.text = f"Hello, {value}!"

layout = MyBoxLayout()

layout.name = "Alice Smith"