Flask mensagens flash como alerta Bootstrap

Flask mensagens flash como alerta Bootstrap.

{% with messages = get_flashed_messages(with_categories=true) %}
  <!-- Categories: success (green), info (blue), warning (yellow), danger (red) -->
  {% if messages %}
    {% for category, message in messages %}
      <div class="alert alert-{{ category }} alert-dismissible" role="alert">
      <button type="button" class="close" data-dismiss="alert" aria-label="Close"><span aria-hidden="true">&times;</span></button>
      <!-- <strong>Title</strong> --> {{ message }}
      </div>
    {% endfor %}
  {% endif %}
{% endwith %}