code: def __iter__(self) -> Iterator[Tuple[str, io.IOBase]]:
      import h5py
  
      for _, handle in self.datapipe:
          try:
              with h5py.File(handle) as data:
                  if self.key is not None:
                      data = data[self.key]
                  yield from data
          finally:
              handle.close()
  
imports: import io
  import pathlib
  from collections import namedtuple
  from typing import Any, Dict, Iterator, List, Optional, Tuple, Union
  from torchdata.datapipes.iter import IterDataPipe, Mapper, Zipper
  from torchvision.prototype.datasets.utils import Dataset, GDriveResource, OnlineResource
  from torchvision.prototype.datasets.utils._internal import hint_sharding, hint_shuffling
  from torchvision.prototype.tv_tensors import Label
  from torchvision.tv_tensors import Image
  from .._api import register_dataset, register_info
label_desc: Use image node_id 2 for calling the PCAMH5Reader obj's underlying member method code with example usage: obj.__iter__() without return types