code: def test_group_class():
      # Moved from grouputils __main__ section
      g = np.array([0, 0, 1, 2, 1, 1, 2, 0])
  
      x = np.arange(len(g) * 3).reshape(len(g), 3, order="F")
      mygroup = Group(g)
  
      mygroup.group_int
      mygroup.group_sums(x)
      mygroup.labels()
  
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 4 for calling a global function with example usage: test_group_class() without return types