Determine which page this post lives on within the topic
        and return link to anchor within that page

def post_url(self):
        """
        Determine which page this post lives on within the topic
        and return link to anchor within that page
        """
        topic = self.topic
        topic_page = topic.post_set.filter(id__lt=self.id).count() / get_paginate_by() + 1
        return "{0}page{1}/#post-{2}".format(topic.get_short_url(), topic_page, self.id)