Why does the function always return 0? (function + tkinter + global variables) [duplicate]

Here is a fragment of my code:

from tkinter import*root = Tk()root.title("Example")root.geometry("1000x250")root['bg']="black"def ask2(question,var1,var2):    ans = 0    def button1():        global ans        bt1.destroy()        bt2.destroy()        lb.destroy()        root.quit()        ans = 0    def button2():        global ans        bt1.destroy()        bt2.destroy()        lb.destroy()        root.quit()        ans = 1    lb = Label(root,text=question,                bg="black",                fg="white",                font=("Determination (RUS BY LYAJKA)",28))    bt1 = Button(text=var1,                 justify=CENTER,                 relief=SOLID,                 bg="black",                 fg="white",                 font=("Determination (RUS BY LYAJKA)",20),                 command=button1,                 disabledforeground="yellow")    bt2 = Button(text=var2,                 justify=CENTER,                 relief=SOLID,                 bg="black",                 fg="white",                 font=("Determination (RUS BY LYAJKA)",20),                 command=button2)    lb.pack(side=TOP)    bt1.pack(side=LEFT)    bt2.pack(side=RIGHT)    root.mainloop()    if ans == 0:        return(0)    else:        return(2)    print(ask2("Question","Answer 1", "Answer 2"))

This function always returns 0. Why?

It's my output (I used the first and the second buttons):enter image description hereI thought that first the program would output 0 and then 2...