code: def clean_abstract(abstract, remove_tags=['xref', 'ext-link', 'inline-formula', 'mml:*']):
      
      if remove_tags:
          for tag_name in remove_tags:
              abstract = utils.remove_tag(tag_name, abstract)
      return abstract
docs: Remove unwanted tags from abstract string,
      parsing it as HTML, then only keep the body paragraph contents