code: def send(self, msg):
      msg.time = time.time()
      self.message_queue.put(msg)
  
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 MockMidiPort obj's underlying member method code with example usage: obj.send(msg) without return types