code: def test_unnest_metrics(self):
      input_data = self._get_per_partition_metrics(n_configurations=2)
      output = list(utility_analysis._unnest_metrics(input_data))
      self.assertLen(output, 4)
      self.assertEqual(output[0], ((0, None), input_data[0]))
      self.assertEqual(output[1], ((0, 100), input_data[0]))
      self.assertEqual(output[2], ((1, None), input_data[1]))
      self.assertEqual(output[3], ((1, 100), input_data[1]))
  
imports: import copy
  from absl.testing import absltest
  from absl.testing import parameterized
  import pipeline_dp
  import analysis
  from analysis import metrics
  from analysis import utility_analysis
  from analysis.tests import common
  from typing import Optional
label_desc: Use image node_id 10 for calling the UtilityAnalysis obj's underlying member method code with example usage: obj.test_unnest_metrics() without return types