code: def testNanPower(self):
      dist = zipf.Zipf(power=np.nan, validate_args=False)
      self.assertAllNan(self.evaluate(dist.power))
  
imports: import numpy
  from scipy import stats
  import tensorflow.compat.v2
  from tensorflow_probability.python.distributions import zipf
  from tensorflow_probability.python.internal import test_util
label_desc: Use image node_id 5 for calling the ZipfTest obj's underlying member method code with example usage: obj.testNanPower() without return types