{% macro nav(request, database=None, table=None) -%}
{% if crumb_items is defined %}
  {% set items=crumb_items(request=request, database=database, table=table) %}
  {% if items %}
    <p class="crumbs">
      {% for item in items %}
        <a href="{{ item.href }}">{{ item.label }}</a>
        {% if not loop.last %}
          /
        {% endif %}
      {% endfor %}
    </p>
  {% endif %}
{% endif %}
{%- endmacro %}