code: def test_empty_sequences(self):
      initial_predictions = torch.LongTensor(
          [self.end_index - 1, self.end_index - 1]
      )
      beam_search = BeamSearch(self.end_index, beam_size=1)
      with pytest.warns(
          RuntimeWarning, match="Empty sequences predicted"
      ):
          predictions, log_probs = beam_search.search(
              initial_predictions, {}, take_step_with_timestep
          )
      # predictions hould have shape `(batch_size, beam_size, max_predicted_length)`.
      assert list(predictions.size()) == [2, 1, 1]
      # log probs hould have shape `(batch_size, beam_size)`.
      assert list(log_probs.size()) == [2, 1]
      assert (predictions == self.end_index).all()
      assert (log_probs == 0).all()
  
imports: from typing import Dict, Tuple, Union
  import numpy
  import pytest
  import torch
  from allennlp.common.checks import ConfigurationError
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.nn.beam_search import MultinomialSampler, BeamSearch, TopKSampler, TopPSampler, GumbelSampler, LengthNormalizedSequenceLogProbabilityScorer, RepeatedNGramBlockingConstraint, StepFunctionTypeWithTimestep, StepFunctionTypeNoTimestep
  from allennlp.common.params import Params
  from allennlp.nn.util import min_value_of_dtype
label_desc: Use image node_id 15 for calling the BeamSearchTest obj's underlying member method code with example usage: obj.test_empty_sequences() without return types