code: def test_multitrack(self):
      # read a multi-track MIDI file
      midi = MIDIFile(pj(ANNOTATIONS_PATH, "multitrack.mid"))
      self.assertTrue(
          np.allclose(
              midi.notes[:4],
              [
                  [0, 60, 0.2272725, 90, 2],
                  [0, 72, 0.90814303, 90, 1],
                  [0.2272725, 67, 0.22632553, 90, 2],
                  [0.45359803, 64, 0.22821947, 90, 2],
              ],
          )
      )
      midi.unit = "b"
      self.assertTrue(
          np.allclose(
              midi.notes[:4],
              [
                  [0, 60, 0.5, 90, 2],
                  [0, 72, 2, 90, 1],
                  [0.5, 67, 0.5, 90, 2],
                  [1, 64, 0.5, 90, 2],
              ],
              atol=1e-2,
          )
      )
  
imports: from __future__ import absolute_import, division, print_function
  import os
  import tempfile
  import unittest
  from os.path import join
  from madmom.io.midi import *
  from .None import ANNOTATIONS_PATH
label_desc: Use image node_id 5 for calling the TestMIDIFileClass obj's underlying member method code with example usage: obj.test_multitrack() without return types