code: def test_dataloader(self) -> MultiDataLoader:
      self.test_loader = self._build_multi_dataloader("test")
      return self.test_loader
  
imports: import logging
  import warnings
  from typing import Dict, List, Optional
  import pytorch_lightning
  from mmf.common.sample import SampleList
  from mmf.common.test_reporter import TestReporter
  from mmf.datasets.iteration_strategies import IterationStrategy
  from mmf.datasets.multi_dataset_loader import MultiDataLoader
  from mmf.utils.build import build_iteration_strategy, build_multiple_datamodules, build_test_reporter
  from mmf.utils.dataset import dataset_list_from_config
  from mmf.utils.general import get_batch_size
  from omegaconf import DictConfig, OmegaConf
  from torch.utils.data import DataLoader
label_desc: Use image node_id 4 for calling the MultiDataModule obj's underlying member method code with example usage: obj.test_dataloader() and returns: self