code: def setup_class(cls):
      formula = "methylation ~ gender + CpG"
      mod = BetaModel.from_formula(
          formula,
          methylation,
          exog_precision_formula="~ age",
          link_precision=links.Log(),
      )
      cls.res1 = mod.fit(cov_type="eim")
      cls.res2 = resultsb.results_meth
  
imports: import io
  import os
  import pytest
  import numpy
  from numpy.testing import assert_allclose, assert_equal
  import pandas
  import patsy
  from statsmodels.api import families
  from statsmodels.tools.sm_exceptions import ValueWarning
  from statsmodels.othermod.betareg import BetaModel
  from .results import results_betareg
label_desc: Use image node_id 1 for calling the TestBetaMeth obj's underlying member method code with example usage: obj.setup_class(cls) without return types