changing tkinter label from thread

[menator01]

Here is my example of changing label text

#! /usr/bin/env python3

import tkinter as tk


class ChangeText:
    def __init__(self, parent):
        self.parent = parent
        self.label = tk.Label(self.parent)
        self.label['text'] = 'Start Text'
        self.label.pack()
        self.update()

    def update(self):
        self.label['text'] = 'Updating in 10'
        self.i = 10
        self.timer()

    def run_timer(self):
        if self.i >= 0:
            self.i -= 1

    def timer(self):
        self.run_timer()
        if self.i >= 0:
            self.label.after(1000, self.timer)
            self.label['text'] = f'Updating in {self.i}'
        else:
            self.label['text'] = f'Done!'




def main():
    root = tk.Tk()
    root.geometry('400x300+100+100')
    root.title('Change Text')
    ChangeText(root)
    root.mainloop()

if __name__ == '__main__':
    main()