code: def test_MICE1(self):
      df = gendat()
      imp_data = mice.MICEData(df)
      mi = mice.MICE("y ~ x1 + x2 + x1:x2", sm.OLS, imp_data)
  
      from statsmodels.regression.linear_model import (
          RegressionResultsWrapper,
      )
  
      for j in range(3):
          x = mi.next_sample()
          assert issubclass(x.__class__, RegressionResultsWrapper)
  
imports: import numpy
  import pandas
  import pytest
  from statsmodels.imputation import mice
  import statsmodels.api
  from numpy.testing import assert_equal, assert_allclose
  import warnings
label_desc: Use image node_id 2 for calling the TestMICE obj's underlying member method code with example usage: obj.test_MICE1() without return types