无法在Mac上运行Pygame游戏，未显示错误

Question

我决定尝试pygame，并想制作一个蛇游戏来上手。我尝试第一次执行它，但没有真正发生任何事情。唯一正在发生的事情是，“ Python火箭”正在打开，但它什么也没做，只是在基座中上下弹跳。 有人知道我能做什么吗？

如果有帮助，请参见以下代码：

# Python Snake Game

import math
import random
import pygame
import tkinter as tk
from tkinter import messagebox

class cube(object):
    rows = 0
    w = 0
    def __init__(self, start, dirnx=1, dirny=0, color=(255, 0, 0)):
        pass

    def move(self, dirnx, dirny):
        pass

    def draw(self, surface, eyes = False):
        pass


class snake(object):
    def __init__(self, color, pos):
        pass

    def move(self):
        pass

    def reset(self, pos):
        pass

    def addCube(self):
        pass

    def draw(self, surface):
        pass


def drawGrid(w, rows, surface):
    sizeBetween = w // rows

    x = 0
    y = 0
    for l in range(rows):
        x = x + sizeBetween
        y = y + sizeBetween

        pygame.draw.line(surface, (255, 255, 255), (x, 0), (x, w))
        pygame.draw.line(surface, (255, 255, 255), (0, y), (w, y))

    pass

def redrawWindow(surface):
    global rows, width
    surface.fill((0, 0, 0))
    drawGrid(width, rows, surface)
    pygame.display.update()
    pass

def randomSnack(rows, items):
    pass

def message_box(subject, content):
    pass

def main():
    global width, rows
    width = 500
    rows = 20
    win = pygame.display.set_mode((width, width))
    s = snake((255, 0, 0), (10, 10))

    flag = True
    clock = pygame.time.Clock()

    while flag:
        pygame.time.delay(50)
        clock.tick(10)

        redrawWindow(win)

    pass


main()

此刻，我只想绘制网格。

谢谢。