class_docstr: Test the private method 'get_samples'.
code: def test_raises_if_both_z_and_n_are_not_none(self):
      dist = normal.Normal(loc=0.0, scale=1.0)
      z = dist.sample(seed=test_util.test_seed())
      n = 1
      seed = test_util.test_seed()
      with self.assertRaisesRegexp(ValueError, "exactly one"):
          _get_samples(dist, z, n, seed)
  
imports: import tensorflow.compat.v2
  from tensorflow_probability.python.distributions import bernoulli
  from tensorflow_probability.python.distributions import joint_distribution_named
  from tensorflow_probability.python.distributions import kullback_leibler
  from tensorflow_probability.python.distributions import normal
  from tensorflow_probability.python.internal import reparameterization
  from tensorflow_probability.python.internal import test_util
  from tensorflow_probability.python.internal.monte_carlo import _get_samples
  from tensorflow_probability.python.math import gradient
  from tensorflow_probability.python.monte_carlo import expectation
label_desc: Use image node_id 2 for calling the GetSamplesTest obj's underlying member method code with example usage: obj.test_raises_if_both_z_and_n_are_not_none() without return types