code: def testAssertsValidSample(self):
      inv_gamma = inverse_gamma.InverseGamma(
          concentration=[3.0, 5.0, 2.0], scale=2.0, validate_args=True
      )
      with self.assertRaisesOpError("Sample must be non-negative."):
          self.evaluate(inv_gamma.cdf([4.0, -1.7, 2.0]))
  
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 21 for calling the InverseGammaTest obj's underlying member method code with example usage: obj.testAssertsValidSample() without return types