【11.7】async和await

python3.5之后，才引入了原生协程的语法

#!/usr/bin/env python
# -*- coding:utf-8 -*-

# python为了将语义变得更加明确，就引入了async和await关键词用于定义原生的协程


async def downloader(url):
    return 'zy'


# 在async中不能yield，await只能出现在async中
async def download_url(url):
    # do somethings
    html = await downloader(url)

    return html


if __name__ == '__main__':
    coro = download_url('http://www.imooc.com')
    # next(coro)不能使用这种方式调用
    coro.send(None)

Traceback (most recent call last):
  File "C:/Users/Administrator/Python/imooc/async_ts/async_await.py", line 22, in <module>
    coro.send(None)
StopIteration: zy