code: def testUnknownShape(self):
      scores = tf1.placeholder_with_default(
          [[1e-6, 1000.0], [1000.0, 1e-6]], shape=None
      )
      dist = plackett_luce.PlackettLuce(scores, validate_args=True)
      sample = dist.sample(seed=test_util.test_seed())
      # Batch entry 0, 1 will sample permutations [1, 0], [0, 1].
      sample_value_batch = self.evaluate(sample)
      self.assertAllEqual([[1, 0], [0, 1]], sample_value_batch)
  
imports: import numpy
  import scipy
  import tensorflow.compat.v1
  import tensorflow.compat.v2
  from tensorflow_probability.python.bijectors import identity
  from tensorflow_probability.python.distributions import plackett_luce
  from tensorflow_probability.python.internal import tensorshape_util
  from tensorflow_probability.python.internal import test_util
  from tensorflow_probability.python.util import deferred_tensor
label_desc: Use image node_id 6 for calling the PlackettLuceTest obj's underlying member method code with example usage: obj.testUnknownShape() without return types