code: def testGumbelStd(self):
      batch_size = 6
      loc = np.array([[2.0, 4.0, 5.0]] * batch_size, dtype=self._dtype)
      scale = np.array([1.0], dtype=self._dtype)
  
      dist = gumbel.Gumbel(
          loc=self.make_tensor(loc),
          scale=self.make_tensor(scale),
          validate_args=True,
      )
  
      self.assertAllClose(
          self.evaluate(dist.stddev()),
          stats.gumbel_r.std(loc=loc, scale=scale),
      )
  
imports: import numpy
  from scipy import stats
  import tensorflow.compat.v1
  import tensorflow.compat.v2
  from tensorflow_probability.python.distributions import gumbel
  from tensorflow_probability.python.distributions import kullback_leibler
  from tensorflow_probability.python.internal import test_util
label_desc: Use image node_id 10 for calling the _GumbelTest obj's underlying member method code with example usage: obj.testGumbelStd() without return types