{% set show_sidebar = show_sidebar is defined ? show_sidebar : true %}
<div class="columns{% if show_sidebar %} has-sidebar{% endif %}">
    <div id="item" class="column extra-spacing">
        {% block item %}{% endblock %}
    </div>
    {% if show_sidebar %}
    <aside id="sidebar" class="column">
        {% block sidebar %}{% endblock %}
    </aside>
    {% endif %}
</div>