code: def test_combine_means(samples, sample_means, expected_mean):
      num_sents = [len(l) for l in samples]
      combined_mean = utils.combine_means(sample_means, num_sents)
      assert np.isclose(expected_mean, combined_mean)
  
imports: import gzip
  import math
  import os
  import re
  from tempfile import TemporaryDirectory
  import unittest
  import numpy
  import pytest
  import torch
  from sockeye import __version__
  from sockeye import constants
  from sockeye import utils
label_desc: Use image node_id 12 for calling a global function with example usage: test_combine_means(samples, sample_means, expected_mean) without return types