code: def nbunch_iter(self, nbunch=None) -> Iterator[NodeKey]:
      if nbunch is None:
          return iter(self)
      if nbunch in self:
          return iter([nbunch])
      return (node for node in nbunch if node in self)
  
imports: from __future__ import annotations
  import operator
  from copy import deepcopy
  from typing import TYPE_CHECKING
  import cupy
  import networkx
  import numpy
  import pylibcugraph
  import nx_cugraph
  from ..utils import index_dtype
label_desc: Use image node_id 27 for calling the Graph obj's underlying member method code with example usage: obj.nbunch_iter(nbunch) and returns: unknown, iter, iter