docs: def _get_netengine_backend(self):
          """
          returns the netengine backend specified in self.backend
          for internal use only
          """
          # extract backend class name, eg: AirOS or OpenWRT
          backend_class_name = self.backend.split('.')[-1]
          # convert to lowercase to get the path
          backend_path = self.backend.lower()
          # import module by its path
          module = import_module(backend_path)
          # get netengine backend class
          BackendClass = getattr(module, backend_class_name)
  
          return BackendClass