code: def testRegression(self):
      input = readVector(join(testdir, "input.txt"))
      expected = readVector(join(testdir, "output.txt"))
      output = Spectrum()(input)
      self.assertAlmostEqualVector(expected, output, 1e-4)
  
file_path: essentia/test/src/unittests/standard/test_spectrum.py
imports: from essentia_test import *
label_desc: Use image node_id 1 for calling the TestSpectrum obj's underlying member method code with example usage: obj.testRegression() without return types