Python tkinter cloase first window while opening second window

I'm trying to close the first window as the second window opens. The first window fails to close, and there is no error message.

This question has a similar problem but was solved by addressing the imported libraries: Tkinter is opening a second windows when the first one is closing

Here's my code, which was taken from here https://www.pythontutorial.net/tkinter/tkinter-toplevel/

import tkinter as tkfrom tkinter import ttkclass Window(tk.Toplevel):    def __init__(self, parent):        super().__init__(parent)        self.geometry('300x100')        self.title('Toplevel Window')        ttk.Button(self,                text='Close',                command=self.destroy).pack(expand=True)class App(tk.Tk):    def __init__(self):        super().__init__()        self.geometry('300x200')        self.title('Main Window')        # place a button on the root window        ttk.Button(self,                text='Open a window',                command=self.open_window).pack(expand=True)    def open_window(self):        window = Window(self)        window.grab_set()        self.destroyif __name__ == "__main__":    app = App()    app.mainloop()

I added in self.destroy in the function def open_window(self). But it doesn't close the window created by this class: class App(tk.Tk).