如何在tkinter中禁用绑定到自己帧的另外两个单选按钮

import tkinter as tk

def disable_buttons():
    button2.config(state=tk.DISABLED)
    button3.config(state=tk.DISABLED)

root = tk.Tk()

var = tk.StringVar()

button1 = tk.Radiobutton(root, text="Button 1", variable=var, value="1")
button1.pack()

button2 = tk.Radiobutton(root, text="Button 2", variable=var, value="2")
button2.pack()

button3 = tk.Radiobutton(root, text="Button 3", variable=var, value="3")
button3.pack()

disable_button = tk.Button(root, text="Disable Buttons", command=disable_buttons)
disable_button.pack()

root.mainloop()