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)) * self.n
      )
  
imports: from __future__ import division, print_function, absolute_import
  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