code: def update(self, stages: Iterable["Stage"]) -> "Index":
      stages = set(stages)
      # we remove existing stages with same hashes at first
      # and then re-add the new ones later.
      stages_set = (set(self.stages) - stages) | stages
      return self.__class__(
          self.repo,
          stages=list(stages_set),
          metrics=self._metrics,
          plots=self._plots,
          params=self._params,
          artifacts=self._artifacts,
      )
  
imports: import logging
  import time
  from collections import defaultdict
  from functools import partial
  from itertools import chain
  from typing import TYPE_CHECKING, Any, Callable, Dict, Iterable, Iterator, List, NamedTuple, Optional, Set, Tuple, Union
  from funcy.debug import format_time
  from dvc.dependency import ParamsDependency
  from dvc.fs import LocalFileSystem
  from dvc.fs.callbacks import DEFAULT_CALLBACK
  from dvc.log import logger
  from dvc.utils.objects import cached_property
label_desc: Use image node_id 6 for calling the Index obj's underlying member method code with example usage: obj.update(stages) and returns: self