code: def test_basic(self):
      x1r = self.x1r
      d1w = self.d1w
  
      assert_almost_equal(x1r.mean(0), d1w.mean, 14)
      assert_almost_equal(x1r.var(0, ddof=d1w.ddof), d1w.var, 14)
      assert_almost_equal(x1r.std(0, ddof=d1w.ddof), d1w.std, 14)
      var1 = d1w.var_ddof(ddof=1)
      assert_almost_equal(x1r.var(0, ddof=1), var1, 14)
      std1 = d1w.std_ddof(ddof=1)
      assert_almost_equal(x1r.std(0, ddof=1), std1, 14)
  
      assert_almost_equal(np.cov(x1r.T, bias=1 - d1w.ddof), d1w.cov, 14)
  
imports: import numpy
  from scipy import stats
  import pandas
  from numpy.testing import assert_, assert_almost_equal, assert_allclose
  from statsmodels.stats.weightstats import DescrStatsW, CompareMeans, ttest_ind, ztest, zconfint
  from statsmodels.tools.testing import Holder
label_desc: Use image node_id 1 for calling the CheckWeightstats1dMixin obj's underlying member method code with example usage: obj.test_basic() without return types