code: def test_merge_dense(self):
      combiner = self._create_combiner()
      dense_count_acc1 = (0, 1, 2, 3)
      acc1 = (None, (1, (dense_count_acc1,)))
      dense_count_acc2 = (0.5, 0.5, 0, -4)
      acc2 = (None, (3, (dense_count_acc2,)))
      sparse, dense = combiner.merge_accumulators(acc1, acc2)
  
      self.assertIsNone(sparse)
      self.assertEqual(dense, (4, ((0.5, 1.5, 2, -1),)))
  
imports: import dataclasses
  import numpy
  from absl.testing import absltest
  from absl.testing import parameterized
  from unittest.mock import patch
  from typing import Tuple
  import pipeline_dp
  from analysis import per_partition_combiners
  from analysis import metrics
  from analysis.tests import common
label_desc: Use image node_id 7 for calling the UtilityAnalysisCompoundCombinerTest obj's underlying member method code with example usage: obj.test_merge_dense() without return types