title: Can Flask use the async feature of Tornado Server?
body: <p>We have a project use Flask+Gunicorn(sync). This works well for a long time,  however, recently i came across to know that Asyncio(Python3.5) support async io in standard library. </p>
  
  <p>However, before Asyncio, there are both Twisted and Tornado async servers. So, i wander whether Flask can use the aysncio feature of Tornado, cause Gunicorn support tornado worker class.</p>