我无法在PyGame中更改类的形状

import pygame

# 初始化PyGame
pygame.init()

# 创建一个窗口
window_width = 800
window_height = 600
window = pygame.display.set_mode((window_width, window_height))

# 设置背景颜色
background_color = (255, 255, 255)

# 游戏主循环
running = True
while running:
    # 处理事件
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

    # 清空窗口
    window.fill(background_color)

    # 绘制矩形
    rect_color = (255, 0, 0)
    rect_position = (100, 100)
    rect_size = (200, 100)
    pygame.draw.rect(window, rect_color, rect_position + rect_size)

    # 更新窗口
    pygame.display.flip()

# 退出PyGame
pygame.quit()