code: def testInverseGammaMeanAllowNanStats(self):
      # Mean will not be defined for the first entry.
      alpha_v = np.array([1.0, 3.0, 2.5])
      beta_v = np.array([1.0, 4.0, 5.0])
      inv_gamma = inverse_gamma.InverseGamma(
          concentration=alpha_v,
          scale=beta_v,
          allow_nan_stats=False,
          validate_args=True,
      )
      with self.assertRaisesOpError("x < y"):
          self.evaluate(inv_gamma.mean())
  
imports: import numpy
  from scipy import stats
  import tensorflow.compat.v2
  from tensorflow_probability.python.distributions import inverse_gamma
  from tensorflow_probability.python.internal import test_util
  from tensorflow_probability.python.math import gradient
label_desc: Use image node_id 9 for calling the InverseGammaTest obj's underlying member method code with example usage: obj.testInverseGammaMeanAllowNanStats() without return types