code: def get_url_for_model(obj):
      
      if obj.__class__ == Section:
          return reverse('section_view', kwargs={'full_slug': obj.full_slug})
      if obj.__class__ == Article:
          return reverse('article_detail', kwargs={'slug': obj.slug})
docs: The get_url_for_model function is necessary because Armstrong has no
      preconceptions about what your url schema actually looks like.
      get_url_for_model is called whenever a BaseContent subclass has it's
      get_absolute_url function calle_url_for_model is called whenever a
      BaseContent subclass has it's get_absolute_url function called.
  
      In the future we will most likely provide base urls for each app that will
      allow new Armstrong implementations to not use this mechanism.