code: def make_back_matter(self):
          
  
          #Back is technically metadata content that needs to be interpreted to
          #presentable content
          body = self.main.getroot().find('body')
          if self.article.root.find('back') is None:
              return
          #The following things are ordered in such a way to adhere to what
          #appears to be a consistent presentation order for PLoS
          #Acknowledgments
          back_ack = self.make_back_acknowledgments()
          if back_ack is not None:
              body.append(back_ack)
          #Author Contributions
          self.make_back_author_contributions(body)
          #Glossaries
          self.make_back_glossary(body)
          #Notes
          self.make_back_notes(body)
docs: The <back> element may have 0 or 1 <label> elements and 0 or 1 <title>
          elements. Then it may have any combination of the following: <ack>,
          <app-group>, <bio>, <fn-group>, <glossary>, <ref-list>, <notes>, and
          <sec>. <sec> is employed here as a catch-all for material that does not
          fall under the other categories.
  
          The Back should generally be thought of as a non-linear element, though
          some of its content will be parsed to the linear flow of the document.
          This can be thought of as critically important meta-information that
          should accompany the main text (e.g. Acknowledgments and Contributions)
  
          Because the content of <back> contains a set of tags that intersects
          with that of the Body, this method should always be called before the
          general post-processing steps; keep in mind that this is also the
          opportunity to permit special handling of content in the Back