{% for level, depths in lessons.items %}
<section class="section-level section-level-{{ level.slug }}">
    {% spaceless %}
    {% for depth, lesson_list in depths.items %}
        <section class="section-depth section-depth-{{ depth }}">
            {% if depth == 0 %}
                <h1>Lekcja syntetyczna</h1>
            {% else %}
                <h1>Pełny kurs</h1>
            {% endif %}
            <ul class="section-lessons">
                {% for lesson in lesson_list %}
                    <li class="section-lesson">
                        <a href="{{ lesson.get_absolute_url }}">{{ lesson }}</a>
                    </li>
                {% endfor %}
            </ul>
        </section>
    {% endfor %}
    {% endspaceless %}
</section>
{% endfor %}