code: def test_bleu_empty_class():
      """Test that bleu returns 0 when no input is provided."""
      bleu = BLEUScore()
      preds = [[]]
      targets = [[[]]]
      assert bleu(preds, targets) == tensor(0.0)
  
imports: from functools import partial
  from typing import Any
  import pytest
  from nltk.translate.bleu_score import SmoothingFunction, corpus_bleu
  from torch import tensor
  from torchmetrics.functional.text.bleu import bleu_score
  from torchmetrics.text.bleu import BLEUScore
  from unittests.text.helpers import TextTester
  from unittests.text.inputs import _inputs_multiple_references
label_desc: Use image node_id 4 for calling a global function with example usage: test_bleu_empty_class() without return types