Alerts in base.html

base.html

<div id="content">
  {% block alerts %}
    {% try %}
      {% if alerts is not None %}
        {% for alert in alerts %}	
          <div class="{{alert.get('level', 'alert') }}">
            {{ alert.get('content') }}
          </div>
        {% end %}
      {% end %}
    {% except NameError %}
    {% end %}
  {% end %}	
  {% block page_content %}{% end %}
</div>