docstr: Test arithmetic_mean()
docstr_tok: ["Test","arithmetic_mean","(",")"]
code: def test_arithmetic_mean(self):
      """Test arithmetic_mean()"""
      obtained = aggregation.arithmetic_mean(self.confirmed_measures)
      expected = 2.75
      self.assertEqual(obtained, expected)
  
imports: import logging
  import unittest
  from gensim.topic_coherence import aggregation
label_desc: Use image node_id 2 for calling the TestAggregation obj's underlying member method code with example usage: obj.test_arithmetic_mean() without return types