class_docstr: A distribution that samples permutations and penalizes item scores.
  
  This distribution samples elements of a permutation incrementally, and after
  every sample it penalizes the scores of the remaining items by the similarity
  of already chosen items.
code: def _event_shape(self, scores=None):
      return self._num_slots
  
imports: from typing import Optional, Sequence, Text
  import numpy
  import tensorflow
  import tensorflow_probability
  from tf_agents.policies import tf_policy
  from tf_agents.policies import utils
  from tf_agents.specs import bandit_spec_utils
  from tf_agents.specs import tensor_spec
  from tf_agents.trajectories import policy_step
  from tf_agents.typing import types
label_desc: Use image node_id 4 for calling the PenalizedPlackettLuce obj's underlying member method code with example usage: obj._event_shape(scores) and returns: self