code: def testAddMatrices(self, left, right, expected):
      self.assertEqual(expected, left + right)
  
file_path: model-analysis/tensorflow_model_analysis/metrics/multi_class_confusion_matrix_metrics_test.py
imports: from absl.testing import parameterized
  import apache_beam
  from apache_beam.testing import util
  import numpy
  import tensorflow
  from tensorflow_model_analysis.eval_saved_model import testutil
  from tensorflow_model_analysis.metrics import metric_types
  from tensorflow_model_analysis.metrics import metric_util
  from tensorflow_model_analysis.metrics import multi_class_confusion_matrix_metrics
label_desc: Use image node_id 1 for calling the MultiClassConfusionMatrixMetricsTest obj's underlying member method code with example usage: obj.testAddMatrices(left, right, expected) without return types