appengine/standard/i18n/templates/index.jinja2 (11 lines of code) (raw):
<!DOCTYPE html>
<html>
{{ get_i18n_js_tag() }}
An internationalized message generated in the Python code: {{ message|e }}<br>
An internationalized message generated in jinja2 template:
{{ gettext('Hello World from Jinja2 template!')|e }}<br>
An internationalized message generated in javascript:
<span id="js-message"></span><br>
<script src="/static/js/main.js" type="text/javascript">
</script>
</html>