code: def test_serialization(self):
      self.run_class_serialization_test(
          ExampleMetric(name="mse"),
          custom_objects={"ExampleMetric": ExampleMetric},
      )
  
imports: import numpy
  from keras import backend
  from keras import initializers
  from keras import metrics
  from keras import ops
  from keras import testing
  from keras.metrics.metric import Metric
label_desc: Use image node_id 6 for calling the MetricTest obj's underlying member method code with example usage: obj.test_serialization() without return types