code: def testHzToMel(self):
      hz = 440
      expected_mel = 1127.01048 * math.log(hz / 700.0 + 1.0)
      self.assertAlmostEqual(expected_mel, hz2mel(hz))
  
file_path: essentia/test/src/unittests/base/test_utils.py
imports: from essentia_test import *
  import math
  import cmath
  import sys
label_desc: Use image node_id 14 for calling the TestUtils obj's underlying member method code with example usage: obj.testHzToMel() without return types