title: Write an async coroutine that's python 2 and 3 compatible
body: <p>Normally to write python 2/3 compatible code you follow a certain style that can be understood by both interpreters, for example: <a href="https://python-future.org/compatible_idioms.html" rel="nofollow noreferrer">https://python-future.org/compatible_idioms.html</a>.</p>
  
  <p>However, because asyncio introduces syntax such as <code>async def</code> and <code>await function()</code>, this will cause a parse error if run under Python 2.</p>
  
  <p>How can you write a library that is python 2 and python 3 compatible that can still provide an asyncio interface? If there is no easy way to do this, is it possible to make a certain async submodule in the library that can only be imported in python 3.5+?</p>