code: def test_unweighted(self):
      rmse_obj = metrics.RootMeanSquaredError()
      y_true = np.array([2, 4, 6])
      y_pred = np.array([1, 3, 2])
  
      rmse_obj.update_state(y_true, y_pred)
      result = rmse_obj.result()
      # error = [-1, -1, -4], square(error) = [1, 1, 16], mean = 18/3 = 6
      self.assertAllClose(np.sqrt(6), result, atol=1e-3)
  
imports: import numpy
  from absl.testing import parameterized
  from keras import testing
  from keras.metrics import regression_metrics
label_desc: Use image node_id 2 for calling the RootMeanSquaredErrorTest obj's underlying member method code with example usage: obj.test_unweighted() without return types