code: def test_upmix(self):
      signal, sample_rate = load_audio_file(sample_file, num_channels=2)
      self.assertTrue(
          np.allclose(
              signal[:5],
              [
                  [-2494, -2494],
                  [-2510, -2510],
                  [-2484, -2484],
                  [-2678, -2678],
                  [-2833, -2833],
              ],
          )
      )
      self.assertTrue(len(signal) == 123481)
      self.assertTrue(sample_rate == 44100)
      self.assertTrue(signal.shape == (123481, 2))
  
imports: from __future__ import absolute_import, division, print_function
  import io
  import unittest
  from os.path import join
  from madmom.io.audio import *
  from .None import AUDIO_PATH, DATA_PATH
label_desc: Use image node_id 7 for calling the TestLoadAudioFileFunction obj's underlying member method code with example usage: obj.test_upmix() without return types