def registerMenu():
    frame = Frame(root)
    Label(frame, text="Register menu").grid(row=1)
    Label(frame, text="Register menu").grid(row=2)
    Label(frame, text="Register menu").grid(row=3)
    username = Entry(frame).grid(row=2, column=2)
    password = Entry(frame).grid(row=3, column=2)
    Button(frame, text="Register",command=lambda: register(username,password))
    return frame

def loginMenu():
    pass


def menu():
    frame = Frame(root)
    Label(frame, text="Menu for guests").grid(row=1)
    Button(frame, text="Register", command=registerMenu).grid(row=2)
    Button(frame, text="Login", command=loginMenu).grid(row=3)
    Button(frame, text="Exit", command=root.destroy).grid(row=4)
    return frame

root = Tk()
menu_frame = menu()
register_frame = registerMenu()
menu_frame.pack(fill="both", expand=True)
root.mainloop()