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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_article_placeholders(self, article):
 """ 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 = {} """

        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()