title: Syntax error installing gunicorn
body: <p>I am following this Heroku tutorial: <a href="https://devcenter.heroku.com/articles/getting-started-with-python-o" rel="noreferrer">https://devcenter.heroku.com/articles/getting-started-with-python-o</a> and when I am trying to install gunicorn in a virtualenv I am getting this error:</p>
  
  <pre><code>(venv)jabuntu14@ubuntu:~/Desktop/helloflask$ pip install gunicorn
  Downloading/unpacking gunicorn
  Downloading gunicorn-19.1.1-py2.py3-none-any.whl (104kB): 104kB downloaded
  Installing collected packages: gunicorn
  Compiling /home/jabuntu14/Desktop/helloflask/venv/build/gunicorn/gunicorn/workers    /_gaiohttp.py ...
  File "/home/jabuntu14/Desktop/helloflask/venv/build/gunicorn/gunicorn/workers    /_gaiohttp.py", line 64
      yield from self.wsgi.close()
           ^
  
  SyntaxError: invalid syntax
  Successfully installed gunicorn
  Cleaning up...
  </code></pre>
  
  <p>However, when I run $foreman start it appears to work properly.</p>
  
  <p>How important is this error? Any idea how to solve it?</p>