code: def get_new_articles(last_seen, assignment_slug=None, brief=False, *args, **kwargs):
      
      if brief:
          return Brief.objects.filter(pub_date__gte=last_seen).order_by('-id')
  
      if assignment_slug:
          return Article.published.filter(assignment__slug=assignment_slug, created__gte=last_seen)
      return Article.published.filter(created__gte=last_seen)
docs: Takes a 'last_seen' timestamp and assignment slug and returns a list.
      Note that you can pass no assignment slug and it will return all articles.
      Pass brief=True to get news briefs
      Usage:
          {% get_new_articles <LAST_SEEN> some_blog as blog_entries %}
          {% get_new_articles <LAST_SEEN> as latest_content %}
          {% get_new_articles <LAST_SEEN> brief=True as news_briefs %}