code: def keys(self):
      index = super().keys
      if self._freq is not None and isinstance(
          index, cudf.DatetimeIndex
      ):
          return cudf.DatetimeIndex._from_data(
              index._data, freq=self._freq
          )
      return index
  
imports: import pickle
  import numpy
  import pandas
  import cudf
  import cudf._lib.labeling
  import cudf.core.index
  from cudf._typing import DataFrameOrSeries
  from cudf.core.groupby.groupby import DataFrameGroupBy, GroupBy, SeriesGroupBy, _Grouping
  from cudf.core.tools.datetimes import _offset_alias_to_code, _unit_dtype_map
label_desc: Use image node_id 3 for calling the _ResampleGrouping obj's underlying member method code with example usage: obj.keys() and returns: index, cudf