code: def setup_class(cls):
      true = {
          "params": np.r_[
              0.7253684,
              0.1641252,
              0.6178282,
              0.2564055,
              0.7994204,
              0.3821718,
              0.5261292,
              -0.0034106,
              0.6015991,
              0.8464551,
              0.9690088,
              0.4178913,
              0.1201952,
              0.0464136,
              0.1075357,
              -0.0425603,
              0.1298906,
              0.9099168,
              0.438375**2,
          ],
          "llf": -189.89493,
          "llf_fit": -182.27188,
          "llf_fit_em": -226.88581,
      }
      super().setup_class(
          true,
          fedfunds[4:],
          k_regimes=3,
          exog=np.c_[fedfunds[3:-1], ogap[4:], inf[4:]],
      )
  
imports: import os
  import warnings
  import numpy
  from numpy.testing import assert_allclose, assert_raises
  import pandas
  import pytest
  from statsmodels.tsa.regime_switching import markov_switching, markov_regression
label_desc: Use image node_id 1 for calling the TestFedFundsConstL1Exog3 obj's underlying member method code with example usage: obj.setup_class(cls) without return types