code: def __init__(self, num_threads):
      self.num_threads = num_threads
      self.waiting = 0
      self.checkin_mutex = thread.allocate_lock()
      self.checkout_mutex = thread.allocate_lock()
      self.checkout_mutex.acquire()
  
imports: import os
  import unittest
  import random
  from test import support
  from test.support import threading_helper
  import _thread
  import time
  import warnings
  import weakref
  from test import lock_tests
label_desc: Use image node_id 1 to create a new Barrier object  with example: obj = Barrier(num_threads)