title: What is function User.findOrCreate doing and when is it called in passport?
body: <p>I can't find documentation on this function and therefor I can't make it work right. When is that function being called, what is it doing and what is it taking as first parameters? I'm trying to get access token from passport, but can't reach it anyhow.</p>
  
  <pre><code>passport.use(new FacebookStrategy({
      clientID:   APP_ID,
      clientSecret:   APP_SECRET,
      callbackURL: "http://localhost:3000/",
    },
    function(accessToken, refreshToken, profile, done) {
      User.findOrCreate({// what are these parameters?}, function (err, user) {
          // when is this function called and what is it doing? 
         });
  
    }
  ));
  </code></pre>
  
  <p>How can I get access token from passport?</p>