code: def demo_paths(self):
          
          base_path = os.path.join(self.module.__path__[0], 'demo')
          paths = []
          if os.path.isdir(base_path):
              for item in os.listdir(base_path):
                  # TODO: support examples which is not auto-loaded
                  if not os.path.isdir(os.path.join(base_path, 'examples')):
                      paths.append(os.path.join(base_path, item))
          return paths
docs: returns collected demo paths excluding examples
          TODO: call super which returns custom paths in descriptor