code: def result(self):
      mse = super().result()
      return {"mse": mse, "one_minus_mse": 1 - mse}
  
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 tf_metric_wrapper
  from tensorflow_model_analysis.proto import config_pb2
label_desc: Use image node_id 2 for calling the _CustomMeanSquaredError obj's underlying member method code with example usage: obj.result() and returns: dict