code: def _groupby_optimized(gb):
      """Check that groupby input can use dask-cudf optimized codepath"""
      return isinstance(gb.obj, DaskDataFrame) and (
          isinstance(gb.by, str)
          or (
              isinstance(gb.by, list)
              and all(isinstance(x, str) for x in gb.by)
          )
      )
  
imports: from functools import wraps
  from typing import Set
  import numpy
  import pandas
  from dask.dataframe.core import DataFrame, aca, split_out_on_cols
  from dask.dataframe.groupby import DataFrameGroupBy, SeriesGroupBy
  from dask.utils import funcname
  import cudf
  from cudf.utils.nvtx_annotation import _dask_cudf_nvtx_annotate
  from dask_cudf.sorting import _deprecate_shuffle_kwarg
label_desc: Use image node_id 7 for calling a global function with example usage: _groupby_optimized(gb) and returns: unknown