Как сделать, чтобы после окончания игры, код начался заново

#!/usr/bin/python3
import pygame
import random
from tkinter import messagebox as msg, Tk
def main():
    pygame.init()

    def draw_grid(scr):
        pygame.draw.line(scr, (0, 0, 0), (100, 0), (100, 300), 3)
        pygame.draw.line(scr, (0, 0, 0), (200, 0), (200, 300), 3)
        pygame.draw.line(scr, (0, 0, 0), (0, 100), (300, 100), 3)
        pygame.draw.line(scr, (0, 0, 0), (0, 200), (300, 200), 3)


    def draw_tic_tac_toe(scr, items):
        for i in range(3):
            for j in range(3):
                if items[i][j] == "0":
                    pygame.draw.circle(scr, (255, 0, 0), (j * 100 + 50, i * 100 + 50), 45)
                elif items[i][j] == "x":
                    pygame.draw.line(scr, (0, 0, 255), (j * 100 + 5, i * 100 + 5), (j * 100 + 95, i * 100 + 95), 3)
                    pygame.draw.line(scr, (0, 0, 255), (j * 100 + 95, i * 100 + 5), (j * 100 + 5, i * 100 + 95), 3)


    def get_win_check(fd, symbol):
        flag_win = False
        global mainloop
        for line in fd:
            if line.count(symbol) == 3:
                flag_win = True
                mainloop = False
        for i in range(3):
            if fd[0][i] == fd[1][i] == fd[2][i] == symbol:
                flag_win = True
        if fd[0][0] == fd[1][1] == fd[2][2] == symbol:
            flag_win = True
        if fd[0][2] == fd[1][1] == fd[2][0] == symbol:
            flag_win = True
        return flag_win

    field = [["", "", ""],
            ["", "", ""],
            ["", "", ""]]

    SCREEN_SIZE = (300, 300)

    window = pygame.display.set_mode(SCREEN_SIZE)
    screen = pygame.Surface(SCREEN_SIZE)

    pygame.display.set_caption("Крестики-нолики")
    screen.fill((255, 255, 255))

    mainloop = True
    game_over = False
        

    while not game_over:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                mainloop = False

            if event.type == pygame.MOUSEBUTTONDOWN and not game_over:
                pos = pygame.mouse.get_pos()
                if field[pos[1] // 100][pos[0] // 100] == "":
                    field[pos[1] // 100][pos[0] // 100] = "x"
                    x, y = random.randint(0, 2), random.randint(0, 2)
                    while field[x][y] != "":
                        x, y = random.randint(0, 2), random.randint(0, 2)
                    field[x][y] = "0"

                player_win = get_win_check(field, "x")
                ai_win = get_win_check(field, "0")
                if player_win or ai_win:
                    game_over = True
                    if player_win:
                        pygame.display.set_caption("Вы победили")
                    else:
                        pygame.display.set_caption("Компьютер победил")
                elif field[0].count("x") + field[0].count("0") + field[1].count("x") + \
                        field[1].count("0") + field[2].count("x") + field[2].count("0") == 8:
                    game_over = True
                    pygame.display.set_caption("Ничья")
        
            

        draw_tic_tac_toe(screen, field)
        draw_grid(screen)
        window.blit(screen, (0, 0))
        pygame.display.update()


play_again = True
while play_again:
    main()
    tk = Tk()
    play_again = msg.askokcancel('Инфо', 'Сыграем еще?')
    tk.destroy()