如何在pygame中停止鼠标点击时变量的增加

import pygame
pygame.init()

window_width = 800
window_height = 600
window = pygame.display.set_mode((window_width, window_height))

mouse_clicked = False

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        elif event.type == pygame.MOUSEBUTTONDOWN:
            mouse_clicked = True
        elif event.type == pygame.MOUSEBUTTONUP:
            mouse_clicked = False
    
    if mouse_clicked:
        # 在这里执行变量的增加操作
        pass
    
    # 在这里更新游戏界面
    pygame.display.update()