docstr: make sure set_triangle_bands works without 
docstr_tok: ["make","sure","set_triangle_bands","works","without"]
code: def test_triangle_freqs_without_norm(self):
      """make sure set_triangle_bands works without"""
      samplerate = 22050
      freq_list = fvec([0, 100, 1000, 10000])
      f = filterbank(len(freq_list) - 2, 1024)
      f.set_norm(0)
      f.set_triangle_bands(freq_list, samplerate)
      expected = f.get_coeffs()
      f.set_norm(1)
      f.set_triangle_bands(fvec(freq_list), samplerate)
      assert_almost_equal(
          f.get_coeffs().T,
          expected.T * 2.0 / (freq_list[2:] - freq_list[:-2]),
      )
  
imports: import numpy
  from numpy.testing import TestCase, assert_equal, assert_almost_equal
  from _tools import assert_warns
  from aubio import fvec, cvec, filterbank, float_type
label_desc: Use image node_id 13 for calling the aubio_filterbank_mel_test_case obj's underlying member method code with example usage: obj.test_triangle_freqs_without_norm() without return types