code: def __len__(self):
      return len(self.dl)
  
imports: import os
  import random
  import sys
  from collections.abc import Mapping
  from unittest.mock import patch
  import numpy
  import pytest
  import torch
  import torch.nn
  from torch.optim import SGD
  from torch.utils.data import BatchSampler, DataLoader, RandomSampler
  import ignite.distributed
  from ignite.engine import Events
  from ignite.engine.deterministic import _set_rng_states, DeterministicEngine, keep_random_state, ReproducibleBatchSampler, update_dataloader
  from ignite.utils import manual_seed
  from tests.ignite.engine import BatchChecker, setup_sampler
label_desc: Use image node_id 2 for calling the OldDataLoader obj's underlying member method code with example usage: obj.__len__() and returns: len