class_docstr: Unit tests for joint distribution class 
class_docstr_tok: ["Unit","tests","for","joint","distribution","class"]
docstr: Computes Variance 
docstr_tok: ["Computes","Variance"]
code: def _compute_variance(self, samples, axis=None):
      """Computes Variance"""
      return np.var(samples, axis)
  
file_path: dragonfly/dragonfly/distributions/unittest_product.py
imports: from __future__ import absolute_import
  import numpy
  from .continuous import Normal, Exponential, ContinuousUniform
  from .product import JointDistribution
  from ..utils.base_test_class import BaseTestClass, execute_tests
label_desc: Use image node_id 4 for calling the JointDistributionTestCase obj's underlying member method code with example usage: obj._compute_variance(samples, axis) and returns: np