code: def testAssertValidSample(self):
      dist = loglogistic.LogLogistic(
          loc=np.log([1.0, 1.0, 4.0]), scale=2.0, validate_args=True
      )
      with self.assertRaisesOpError("Sample must be non-negative."):
          self.evaluate(dist.cdf([3.0, -0.2, 1.0]))
  
imports: import numpy
  from scipy import stats
  from tensorflow_probability.python.distributions import loglogistic
  from tensorflow_probability.python.internal import test_util
label_desc: Use image node_id 18 for calling the LogLogisticTest obj's underlying member method code with example usage: obj.testAssertValidSample() without return types