code: def __init__(self) -> None:
      self._combined_loader: Optional[CombinedLoader] = None
      self.iterator: Optional[Iterator] = None
      self.fetched: int = 0
      self.done: bool = False
      self.length: Optional[int] = None
      self._start_profiler = _profile_nothing
      self._stop_profiler = _profile_nothing
  
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 1 to create a new _DataFetcher object from inherited base classes: Iterator with example: obj = _DataFetcher()