code: def __len__(self):
      return self.num_batches
  
imports: from typing import Callable, Dict
  import torch
  from torch.utils.data import Dataset
  import torchvision.transforms.functional
  from torchvision import transforms
  import pytorch_lightning
  from collections.abc import Iterable
  from pathlib import Path
  from PIL import Image
  from typing import Tuple
label_desc: Use image node_id 4 for calling the DataDictLoader obj's underlying member method code with example usage: obj.__len__() and returns: self