code: def get_article_placeholders(self, article):
          
          placeholders_search_list = getattr(settings, 'CMS_ARTICLES_PLACEHOLDERS_SEARCH_LIST', {})
  
          included = placeholders_search_list.get('include', [])
          excluded = placeholders_search_list.get('exclude', [])
          diff = set(included) - set(excluded)
          if diff:
              return article.placeholders.filter(slot__in=diff)
          elif excluded:
              return article.placeholders.exclude(slot__in=excluded)
          else:
              return article.placeholders.all()
docs: In the project settings set up the variable
  
          CMS_ARTICLES_PLACEHOLDERS_SEARCH_LIST = {
              'include': [ 'slot1', 'slot2', etc. ],
              'exclude': [ 'slot3', 'slot4', etc. ],
          }
  
          or leave it empty
  
          CMS_ARTICLES_PLACEHOLDERS_SEARCH_LIST = {}