title: passport.js with multiple authentication providers?
body: <p>Using Passport.js is there a way for me to specify multiple authentication providers for the same route?</p>
  
  <p>For example (from passport's guide) can I use local and facebook and twitter strategies on the sample route below?</p>
  
  <pre><code>app.post('/login',
    passport.authenticate('local'), /* how can I add other strategies here? */
    function(req, res) {
      // If this function gets called, authentication was successful.
      // `req.user` contains the authenticated user.
      res.redirect('/users/' + req.user.username);
    });
  </code></pre>