code: def all(self):
          
          class_list = list(self.get_class_list())
          if not class_list:
              self.cache = []
              return []
  
          if self.cache is not None:
              return self.cache
  
          results = []
          for cls_path in class_list:
              module_name, class_name = cls_path.rsplit('.', 1)
              try:
                  module = __import__(module_name, {}, {}, class_name)
                  cls = getattr(module, class_name)
                  if self.instances:
                      results.append(cls())
                  else:
                      results.append(cls)
              except Exception:
                  logger.exception('Unable to import {cls}'.format(cls=cls_path))
                  continue
          self.cache = results
  
          return results
docs: Returns a list of cached instances.