atr/templates/macros/flash.html

{% macro render_flash_messages() %}
  {% with messages = get_flashed_messages(with_categories=true) %}
    {% if messages %}
      {% for category, message in messages %}
        <div class="flash-message flash-{{ category }}">
          {% if category == 'error' %}<strong>Error:</strong>{% endif %}
          {{ message }}
        </div>
      {% endfor %}
    {% endif %}
  {% endwith %}
{% endmacro %}