code: def get_entry_tags(self, categories):
          
          tags = []
          for category in categories:
              domain = category.attrib.get('domain', 'category')
              if 'tag' in domain and category.attrib.get('nicename'):
                  tags.append(category.attrib.get('nicename'))
          return tags
docs: Return a list of entry's tags,
          by using the nicename for url compatibility.