code: def setup_class(cls):
      grun_data = grunfeld.load_pandas().data
      multi_index_data = grun_data.set_index(["firm", "year"])
      multi_index_panel = multi_index_data.index
      cls.grouping = Grouping(multi_index_panel)
      cls.data = multi_index_data
  
      cls.expected_counts = [20] * 11
  
imports: from statsmodels.compat.pandas import assert_frame_equal, assert_series_equal
  import numpy
  from numpy.testing import assert_equal
  import pandas
  import pytest
  from scipy import sparse
  from statsmodels.tools.grouputils import dummy_sparse, Grouping, Group, combine_indices, group_sums
  from statsmodels.datasets import grunfeld, anes96
label_desc: Use image node_id 1 for calling the TestMultiIndexGrouping obj's underlying member method code with example usage: obj.setup_class(cls) without return types