title: Indicate a specific .mo file for Babel to load
body: <p>The setup of the problem is simple enough:</p>
  
  <ul>
  <li>an user selects a language preference (this preference can be read from the user’s session);</li>
  <li>based on this choice, load the appropriate .mo from the available translations;</li>
  <li>(no separate domains are set up, if it makes any difference)</li>
  </ul>
  
  <p>Problem: since this return has to be done outside the scope of the flask app, it cannot be instantiated and to use @babel.localeselector. Instead, I use a simple function based on webapp2 i18n’ extension which, using Babel’s support function, loads a given translation and returns a translation instance (Translations: "PROJECT VERSION"). (inb4 ‘why not use webapp2 already?’ too many libs already).</p>
  
  <p>From this point on, it is not clear to me what to do with this instance. How can I get Babel to use this specific instance? (at the moment, it always uses the default one, no 'best_match' involved).</p>