Tkinter advanced: more windows that you can open once

I made some changes to my code to use more windows in tkinter and I thought I would post it here to let you know. See ya soon guys.

'''
    This let you create more windows,
    but you cannot open the same one
    more than once.
'''


import tkinter as tk


class Win1:
    def __init__(self, master):
        self.master = master
        self.master.geometry("400x300")
        self.show_widgets()

    def show_widgets(self):
        self.frame = tk.Frame(self.master)
        self.master.title("Window n.1")
        self.create_button("Click to open Window 2", Win2)
        self.create_button("Click to open Window 3", Win3)
        self.frame.pack()

    def create_button(self, text, _class):
        "Button that creates a new window"
        tk.Button(
            self.frame, text=text,
            command=lambda: self.new_window(_class)).pack()

    def new_window(self, _class):
            global win2, win3

            try:
                if _class == Win2:
                    if win2.state() == "normal":
                        win2.focus()
            except:  
                win2 = tk.Toplevel(self.master)
                _class(win2)

            try:
                if _class == Win3:
                    if win3.state() == "normal":
                        win3.focus()
            except:  
                win3 = tk.Toplevel(self.master)
                _class(win3)

    def close_window(self):
        self.master.destroy()

class Win2(Win1):

    def show_widgets(self):
        "A frame with a button to quit the window"
        self.master.title("Window 2")
        self.frame = tk.Frame(self.master, bg="red")
        self.quit_button = tk.Button(
            self.frame, text=f"Quit this window n. 2",
            command=self.close_window)
        self.quit_button.pack()
        self.create_button("Open window 3 from window 2", Win3)
        self.frame.pack()



class Win3(Win2):

    def show_widgets(self):
        self.master.title("Window 3")
        self.frame = tk.Frame(self.master, bg="green")
        self.quit_button = tk.Button(
            self.frame, text=f"Quit this window n. 3",
            command=self.close_window)
        self.label = tk.Label(
            self.frame, text="THIS IS ONLY IN THE THIRD WINDOW")
        self.label.pack()
        self.frame.pack()



root = tk.Tk()
app = Win1(root)
root.mainloop()

You will soon find a new repository for the tkinter_book scripts, stay tuned.