title: Is there a way to run 2to3 with pip install?
body: <p>I'm trying to maintain dependencies using <code>pip install -r requirements.txt</code>. However, some of required packages do not support Python 3 directly, but can be converted manually using <code>2to3</code>. </p>
  
  <p>Is there a way to force <code>pip</code> to run <code>2to3</code> on those packages automagically when doing <code>pip install -r requirements.txt</code>?</p>