title: Check if user is logged in with Flask-Login in template
body: <p>When I log a user in, I set <code>logged_in</code> in the session, then check this value in the template.  Is there a better way to check if the user is logged in with Flask-Login?</p>
  
  <pre><code>session['logged_in'] = True
  login_user(user)
  </code></pre>
  
  <pre class="lang-none prettyprint-override"><code>{% if session['logged_in'] %}
      ...
  {% endif %}
  </code></pre>