code: def __len__(self) -> int:
      raise NotImplementedError
  
imports: import contextlib
  from collections.abc import Iterable
  from typing import Any, Callable, Dict, Iterator, List, Literal, Optional, Tuple, Type, Union
  from torch.utils.data.dataloader import _BaseDataLoaderIter, _MultiProcessingDataLoaderIter
  from typing_extensions import Self, TypedDict
  from lightning.fabric.utilities.data import sized_len
  from lightning.pytorch.utilities._pytree import _map_and_unflatten, _tree_flatten, tree_unflatten
label_desc: Use image node_id 4 for calling the _ModeIterator obj's underlying member method code with example usage: obj.__len__() without return types