code: def testNegativeBinomialStddev(self):
      total_count = 5.0
      probs = np.array([0.1, 0.3, 0.25], dtype=np.float32)
      negbinom = negative_binomial.NegativeBinomial(
          total_count=total_count, probs=probs, validate_args=True
      )
      expected_stds = stats.nbinom.std(n=total_count, p=1 - probs)
      self.assertEqual([3], negbinom.stddev().shape)
      self.assertAllClose(
          expected_stds, self.evaluate(negbinom.stddev())
      )
  
imports: import numpy
  from scipy import stats
  import tensorflow.compat.v1
  import tensorflow.compat.v2
  from tensorflow_probability.python.distributions import negative_binomial
  from tensorflow_probability.python.internal import test_util
  from tensorflow_probability.python.math import gradient
label_desc: Use image node_id 17 for calling the NegativeBinomialTest obj's underlying member method code with example usage: obj.testNegativeBinomialStddev() without return types