code: def model_manager(self):
      model_manager = self._model_manager
      assert model_manager
      return model_manager
  
imports: import abc
  import logging
  import pickle
  from typing import Dict, List, NamedTuple, Optional, Tuple
  from reagent.core.parameters import NormalizationData
  from reagent.data.data_fetcher import DataFetcher
  from reagent.data.oss_data_fetcher import OssDataFetcher
  from reagent.preprocessing.batch_preprocessor import BatchPreprocessor
  from reagent.workflow.types import Dataset, ReaderOptions, ResourceOptions, RewardOptions, TableSpec
  from .reagent_data_module import ReAgentDataModule
label_desc: Use image node_id 5 for calling the ManualDataModule obj's underlying member method code with example usage: obj.model_manager() and returns: model_manager