title: Python/Flask/Jinja url_for formatting
body: <p>I'm looking to use Flask's url_for to generate URLs for tags - however it appears to be replacing '+' with the entity/url code '%2B'.  This makes for a rather ugly URL, '+' would be much preferred.</p>
  
  <p>So, my question is, how can I use url_for - but have it accept '+' without formatting it to a HTML entity?</p>