code: def nav_title(self, article):
          
          article_title = article.metadata.front.article_meta.title_group.article_title.node
          return str(etree.tostring(article_title, method='text', encoding='utf-8'), encoding='utf-8')
docs: Frontiers method.
  
          Given an Article class instance, this will return a string representing
          the title of the article. This is done for PloS by serializing the text
          in the Article's