getting the related entries with a templatetag using django-tagging

{% block related %}
<div id="related-posts"><h2>{% trans "Related posts" %}</h2>
{% for tag in object.get_tags %}
	{% tagged_objects tag in blog.Post as relatedItems %}
	{% if relatedItems|length_is:"0" %}
	{% else %}
	<h3>{{ tag }}</h3>
	<ul>
	{% for relatedItem in relatedItems|slice:":3" %}
	<li><a href="{{ relatedItem.get_absolute_url }}">{{ relatedItem.name|typogrify }}</a></li>
	{% endfor %}
	</ul>
	{% endif %}
{% endfor %}
</div>
{% endblock %}