code: def __next__(self) -> _ITERATOR_RETURN:
      n = len(self.iterables)
      if n == 0 or self._iterator_idx >= n:
          raise StopIteration
  
      # if limits are set, go to the correct iterator
      if self.limits is not None:
          while self.limits[self._iterator_idx] <= self._idx:
              self._use_next_iterator()
              if self._iterator_idx >= n:
                  raise StopIteration
  
      try:
          out = next(self.iterators[0])
      except StopIteration:
          # try the next iterator
          self._use_next_iterator()
          return self.__next__()
      index = self._idx
      self._idx += 1
      return out, index, self._iterator_idx
  
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 2 for calling the _Sequential obj's underlying member method code with example usage: obj.__next__() and returns: out,  index,  self, self