{% macro sub_navigation(
  item_set
) %}
  <nav class="sub-navigation">
    <ol itemscope itemtype="http://schema.org/ItemList">
      {% for item in item_set %}        
        <li class="sub-navigation__item {% if item['link'] == request.endpoint %} sub-navigation__item--active {% endif %}" 
            itemprop="itemListElement" 
            itemscope 
            itemtype="http://schema.org/ListItem"
        >
          <a href="{%- if item['external_link'] -%} 
                     {{ item['link'] }} 
                   {%- else -%} 
                     {{ url_for(item['link']) }} 
                   {%- endif -%}" 
             itemprop="item">
            <span itemprop="name">{{item['name']}}</span>
          </a>
        </li>
      {% endfor %}
    </ol>
  </nav>
{% endmacro %}
{% macro sub_navigation(
  item_set
) %}
  <nav class="sub-navigation">
    <ol itemscope itemtype="http://schema.org/ItemList">
      {% for item in item_set %}
        <li class="sub-navigation__item {% if item['link'] == request.endpoint %} sub-navigation__item--active {% endif %}"
            itemprop="itemListElement"
            itemscope
            itemtype="http://schema.org/ListItem"
        >
          <a href="{{ url_for(item['link']) }}" itemprop="item">
            <span itemprop="name">{{item['name']}}</span>
          </a>
        </li>
      {% endfor %}
    </ol>
  </nav>
{% endmacro %}

Remove external link support in sub navigation
Remove external link support in sub navigation

This navigation will only have internal links in it.
