code: def tearDown(self):
      self.midi_hub.__del__()
  
imports: import collections
  import queue
  import threading
  import time
  from magenta.common import concurrency
  from magenta.interfaces.midi import midi_hub
  import mido
  from note_seq import testing_lib
  from note_seq.protobuf import music_pb2
  import tensorflow.compat.v1
label_desc: Use image node_id 2 for calling the MidiHubTest obj's underlying member method code with example usage: obj.tearDown() without return types