code: def _compute_covariance(self):
      self.inv_cov = np.linalg.inv(self.covariance)
      self._norm_factor = np.sqrt(
          np.linalg.det(2 * np.pi * self.covariance)
      )
  
imports: from scipy import stats
  import numpy
  from numpy.testing import assert_almost_equal, assert_, assert_array_almost_equal, assert_array_almost_equal_nulp, assert_allclose
  import pytest
  from pytest import raises
label_desc: Use image node_id 2 for calling the _kde_subclass3 obj's underlying member method code with example usage: obj._compute_covariance() without return types