code: def __next__(self) -> _ITERATOR_RETURN:
      assert self.iterator is not None
      self._start_profiler()
      try:
          batch = next(self.iterator)
      except StopIteration:
          self.done = True
          raise
      finally:
          self._stop_profiler()
      self.fetched += 1
      if self.length is not None:
          self.done = self.fetched >= self.length
      return batch
  
imports: from typing import Any, Iterator, List, Optional
  from typing_extensions import override
  from lightning.fabric.utilities.data import sized_len
  from lightning.pytorch.utilities.combined_loader import _ITERATOR_RETURN, CombinedLoader
  from lightning.pytorch.utilities.exceptions import MisconfigurationException
label_desc: Use image node_id 5 for calling the _DataFetcher obj's underlying member method code with example usage: obj.__next__() and returns: batch