code: def __getitem__(self, key):
      if isinstance(key, list):
          g = CudfDataFrameGroupBy(
              self.obj,
              by=self.by,
              slice=key,
              sort=self.sort,
              **self.dropna,
          )
      else:
          g = CudfSeriesGroupBy(
              self.obj,
              by=self.by,
              slice=key,
              sort=self.sort,
              **self.dropna,
          )
  
      g._meta = g._meta[key]
      return g
  
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 2 for calling the CudfDataFrameGroupBy obj's underlying member method code with example usage: obj.__getitem__(key) and returns: g