1. * 用于展开/收集元组， ** 用于展开/收集字典
2. request类库：http://docs.python-requests.org/zh_CN/latest/
3. 计算图片MD5，如果MD5一致，判断为同一张图片

    def calMD5(url):
      r = requests.get(url)
      imgBytes = r.content 
      hl = hashlib.md5()
      hl.update(imgBytes)
      re = hl.hexdigest()
      return re

4. 异步HTTP库aiohttp: https://hubertroy.gitbooks.io/aiohttp-chinese-documentation/content/
   • 配置ssl证书：

        sslcontext = ssl.create_default_context(cafile='/test.crt')
        async with aiohttp.ClientSession() as session:
            async with session.post('/',data='',ssl_context=sslcontext) as r:

5. 协程：https://docs.python.org/3/library/asyncio-task.html
   • 控制协程并发数量：

        sema = asyncio.Semaphore(2)
        with (await sema):
            sslcontext........
            async ..........