code: def testRegression(self):
      mags = [1.23, 4.32, 1.22, 6.23]
      evenEnergy = mags[0] ** 2 + mags[2] ** 2
      oddEnergy = mags[1] ** 2 + mags[3] ** 2
      self.assertAlmostEqual(
          OddToEvenHarmonicEnergyRatio()(list(range(len(mags))), mags),
          oddEnergy / evenEnergy,
          1e-6,
      )
  
file_path: essentia/test/src/unittests/tonal/test_oddtoevenharmonicenergyratio.py
imports: from essentia_test import *
label_desc: Use image node_id 9 for calling the TestOddToEvenHarmonicEnergyRatio obj's underlying member method code with example usage: obj.testRegression() without return types