Progressbar with start and stop

[jelo34]

Hello,I a Python beginner and am unable to code a scrpit coding for for a window with a start button and a stop button able to start an stop a progressbar in tkinter. My script start the proression but cannot stop it.
Thanks for your help!!

import tkinter as tk
from tkinter import *


def create_window():
    from tkinter import ttk
    import time
    
    def start():
        for x in range (5):
            myprogress['value']+=20
            root.update_idletasks()
            time.sleep(1)
            print(myprogress['value'])


    def stop():
        myprogress.stop()
    
    root= Tk()
    root.geometry("660x400")
    myprogress=ttk.Progressbar(root, orient=HORIZONTAL, length=300, mode='indeterminate')
    myprogress.pack(pady=20)
    mybutton=Button(root, text="start", command=start)
    mybutton.pack(pady=20)
    mybuttonstop=Button(root, text="stop", command=stop)
    mybuttonstop.pack(pady=20)
    root.mainloop()

root = tk.Tk() 
b = tk.Button(root, text="Create new window", command=create_window)
b.grid(row=4, column=3, sticky=W+E, padx=10, pady=20)
 
root.mainloop()