code: def register_entity(self, entity_config):
          
          if not issubclass(entity_config, EntityConfig):
              raise ValueError('Must register entity config class of subclass EntityConfig')
  
          if entity_config.queryset is None:
              raise ValueError('Entity config must define queryset')
  
          model = entity_config.queryset.model
  
          self._entity_registry[model] = entity_config()
  
          # Add watchers to the global look up table
          for watching_model, entity_model_getter in entity_config.watching:
              self._entity_watching[watching_model].append((model, entity_model_getter))
docs: Registers an entity config