title: Uploading different versions (python 2.7 vs 3.5) to PyPI
body: <p>I have a package I'm uploading to PyPI with two different versions of the code: one for Python 2.7 and one for Python 3.5.</p>
  
  <p>What is the standard for uploading this to PyPI? Do I use two separate <code>setup.py</code> files? </p>
  
  <p>When users run <code>pip install mypackage</code> will it automatically download the correct version? </p>