如何在Pygames中简化多个敌人的创建？

import pygame
import random

# 定义敌人类
class Enemy(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()
        self.image = pygame.Surface((30, 30))
        self.image.fill((255, 0, 0))
        self.rect = self.image.get_rect()
        self.rect.x = random.randint(0, 570)
        self.rect.y = random.randint(-100, -40)
        self.speed = random.randint(1, 3)

    def update(self):
        self.rect.y += self.speed
        if self.rect.y > 600:
            self.rect.x = random.randint(0, 570)
            self.rect.y = random.randint(-100, -40)
            self.speed = random.randint(1, 3)

# 初始化Pygame
pygame.init()

# 创建游戏窗口
screen = pygame.display.set_mode((600, 600))

# 创建敌人组
enemies = pygame.sprite.Group()

# 创建多个敌人对象并添加到敌人组
for _ in range(10):
    enemy = Enemy()
    enemies.add(enemy)

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

    # 更新敌人位置
    enemies.update()

    # 绘制游戏界面
    screen.fill((255, 255, 255))
    enemies.draw(screen)
    pygame.display.flip()

# 退出游戏
pygame.quit()