code: def test_create_accumulator(self):
      combiner = self._create_combiner()
      data = [1, 2, 3]
      n_partitions = 500
      sparse, dense = combiner.create_accumulator(
          (len(data), sum(data), n_partitions)
      )
      self.assertEqual(
          ([len(data)], [sum(data)], [n_partitions]), sparse
      )
      self.assertIsNone(dense)
  
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 3 for calling the UtilityAnalysisCompoundCombinerTest obj's underlying member method code with example usage: obj.test_create_accumulator() without return types