{% block scripts %}
  {% block synchronous_scripts %}
  <script type="text/javascript">
    var xsrf_token = '{{xsrf_token}}';
  </script>
  <script type='text/javascript' src="/js/{{ app_version }}/LABjs/LAB.js"></script>
  {% endblock synchronous_scripts %}
  <script>alert("Hi");</script>
...