利用协程框架批量下载网页内容，看看效果吧

import  time import  asyncio  async def down(url):     print("你好，开始下载")     await  asyncio.sleep(3)     print("你好，下载完成")   async def main():     urls =[         'www.baidu.com',         'www.google.com'         'www.163.com'     ]     masks=[]     for url in urls:         p= down(url)         masks.append(p)     done,pending=await asyncio.wait(masks)     for task in done:         print(f"{task}已完成下载")  if __name__ == '__main__':     t1=time.time()     asyncio.run(main())     t2=time.time()     print(t2-t1)