title: Context processor using Werkzeug and Jinja2
body: <p>My application is running on App Engine and is implemented using <a href="http://werkzeug.pocoo.org/" rel="nofollow noreferrer">Werkzeug</a> and <a href="http://jinja.pocoo.org/2/" rel="nofollow noreferrer">Jinja2</a>. I'd like to have something functionally equivalent of Django's own context processor: a callable that takes a request and adds something to the template context. I already have a "context processors" that add something to the template context, but how do I get this <em>request</em> part working? I implemented context processors as a callables that just return a dictionary that later is used to update context.</p>
  
  <p>For example, I'd like to add something that is contained in <code>request.environ</code>.</p>