code: def test_mse(self) -> None:
      mse = cflearn.api.make_metric("mse")
      labels = np.array([1, 1, 1, 1]).reshape([4, 1])
      predictions = np.array([-0.2, -0.1, 0.1, 0.2]).reshape([4, 1])
      self.assertAlmostEqual(
          _get_score(mse, predictions, labels), -1.025
      )
  
file_path: carefree-learn/tests/test_metrics.py
imports: import cflearn
  import unittest
  import numpy
  from cflearn.schema import IMetric
  from cflearn.constants import LABEL_KEY
  from cflearn.constants import PREDICTIONS_KEY
label_desc: Use image node_id 4 for calling the TestMetrics obj's underlying member method code with example usage: obj.test_mse() without return types