code: def test_meltohz(self):
      assert_equal(meltohz(0.0), 0.0)
      assert_almost_equal(meltohz(2), 400.0 / 3.0, decimal=4)
      try:
          assert_equal(meltohz(3.0), 200.0)
      except AssertionError:
          if not is32bit():
              raise
          assert_almost_equal(meltohz(3.0), 200.0, decimal=5)
      assert_almost_equal(meltohz(5), 1000.0 / 3.0, decimal=4)
      assert_almost_equal(meltohz(15), 1000.0, decimal=4)
      assert_almost_equal(meltohz(42), 6400.0, decimal=2)
      assert_almost_equal(meltohz(69), 40960.0, decimal=1)
  
      for f in np.linspace(0, 20000, 1000):
          assert_almost_equal(meltohz(hztomel(f)) - f, 0, decimal=1)
  
imports: from unittest import main
  from numpy.testing import TestCase
  from numpy.testing import assert_equal, assert_almost_equal
  from _tools import assert_warns
  from utils import is32bit
  import numpy
  import aubio
  from aubio import hztomel, meltohz
  from aubio import hztomel_htk, meltohz_htk
label_desc: Use image node_id 2 for calling the aubio_hztomel_test_case obj's underlying member method code with example usage: obj.test_meltohz() without return types