code: def build_mock_groupby(self, **kwargs):
      in_df = self.inputs[0]
      if self.is_dataframe_obj:
          mock_obj = build_df(
              in_df, size=[2, 2], fill_value=[1, 2], ensure_string=True
          )
      else:
          mock_obj = build_series(
              in_df,
              size=[2, 2],
              fill_value=[1, 2],
              name=in_df.name,
              ensure_string=True,
          )
  
      new_kw = self.groupby_params
      new_kw.update(kwargs)
      if new_kw.get("level"):
          new_kw["level"] = 0
      if isinstance(new_kw["by"], list):
          new_by = []
          for v in new_kw["by"]:
              if isinstance(v, ENTITY_TYPE):
                  build_fun = build_df if v.ndim == 2 else build_series
                  mock_by = pd.concat(
                      [
                          build_fun(
                              v, size=2, fill_value=1, name=v.name
                          ),
                          build_fun(
                              v, size=2, fill_value=2, name=v.name
                          ),
                      ]
                  )
                  new_by.append(mock_by)
              else:
                  new_by.append(v)
          new_kw["by"] = new_by
      return mock_obj.groupby(**new_kw)
  
imports: import itertools
  from functools import partial
  import numpy
  import pandas
  from ...None import opcodes
  from ...core import ENTITY_TYPE, Entity, OutputType
  from ...core.operand import OperandStage, MapReduceOperand
  from ...lib.groupby_wrapper import wrapped_groupby
  from ...serialization.serializables import BoolField, Int32Field, AnyField
  from ...utils import lazy_import, pd_release_version, no_default
  from ..align import align_dataframe_series, align_series_series
  from ..initializer import Series
  from ..core import SERIES_TYPE, SERIES_CHUNK_TYPE
  from ..utils import build_concatenated_rows_frame, hash_dataframe_on, build_df, build_series, parse_index, is_cudf
  from ..operands import DataFrameOperandMixin, DataFrameShuffleProxy
label_desc: Use image node_id 10 for calling the DataFrameGroupByOperand obj's underlying member method code with example usage: obj.build_mock_groupby() and returns: mock_obj