code: def calculate(cls):
      cls.g = g = GroupSorted(cls.gind)  # pylint: disable-msg=W0201
      cls.alla = [
          (
              lag,
              sw.lagged_groups(cls.x, lag, g.groupidx),
          )  # pylint: disable-msg=W0201
          for lag in range(5)
      ]
  
file_path: statsmodels/statsmodels/stats/tests/test_groups_sw.py
imports: import numpy
  from numpy.testing import assert_equal, assert_raises
  import statsmodels.stats.sandwich_covariance
  from statsmodels.tools.grouputils import GroupSorted
label_desc: Use image node_id 1 for calling the CheckPanelLagMixin obj's underlying member method code with example usage: obj.calculate(cls) without return types