code: def bleu(items):
      """The Bilingual Evaluation Understudy Score, or BLEU for short, is a metric
      for evaluating a generated sentence to a reference sentence. It counts matching
      n-grams in the candidate translation to n-grams in the reference text, where
      1-gram or unigram would be each token and a bigram comparison would be each
      word pair. The comparison is made regardless of word order
      Source: https://machinelearningmastery.com/calculate-bleu-score-for-text-python/
      Paper: https://www.aclweb.org/anthology/P02-1040/
  
      Higher is better
      """
      refs = list(zip(*items))[0]
      preds = list(zip(*items))[1]
      refs, preds = _sacreformat(refs, preds)
      return sacrebleu.corpus_bleu(preds, refs).score
  
imports: import math
  from collections.abc import Iterable
  import numpy
  import sacrebleu
  import sklearn.metrics
  import random
  from collections import defaultdict
label_desc: Use image node_id 17 for calling a global function with example usage: bleu(items) and returns: sacrebleu