code: def fetch_single_representation(self, item_xlink_href):
          
          #A dict of URLs for PLoS subjournals
          journal_urls = {'pgen': 'http://www.plosgenetics.org/article/{0}',
                          'pcbi': 'http://www.ploscompbiol.org/article/{0}',
                          'ppat': 'http://www.plospathogens.org/article/{0}',
                          'pntd': 'http://www.plosntds.org/article/{0}',
                          'pmed': 'http://www.plosmedicine.org/article/{0}',
                          'pbio': 'http://www.plosbiology.org/article/{0}',
                          'pone': 'http://www.plosone.org/article/{0}',
                          'pctr': 'http://clinicaltrials.ploshubs.org/article/{0}'}
          #Identify subjournal name for base URl
          subjournal_name = self.article.doi.split('.')[2]
          base_url = journal_urls[subjournal_name]
          #Compose the address for fetchSingleRepresentation
          resource = 'fetchSingleRepresentation.action?uri=' + item_xlink_href
          return base_url.format(resource)
docs: This function will render a formatted URL for accessing the PLoS' server
          SingleRepresentation of an object.