code: def test_wait(self):
      for i in range(NUM_THREADS):
          thread = threading.Thread(target=self.f, args=(i,))
          thread.start()
          self.threads.append(thread)
  
      # busy-loop to wait for threads
      for _ in support.sleeping_retry(support.SHORT_TIMEOUT):
          if len(self.alive) >= NUM_THREADS:
              break
  
      a = sorted(self.alive.keys())
      self.assertEqual(a, list(range(NUM_THREADS)))
  
      prefork_lives = self.alive.copy()
  
      # Ignore the warning about fork with threads.
      with warnings.catch_warnings(
          category=DeprecationWarning, action="ignore"
      ):
          if (cpid := os.fork()) == 0:
              # Child
              time.sleep(LONGSLEEP)
              n = 0
              for key in self.alive:
                  if self.alive[key] != prefork_lives[key]:
                      n += 1
              os._exit(n)
          else:
              # Parent
              self.wait_impl(cpid, exitcode=0)
  
file_path: cpython/Lib/test/fork_wait.py
imports: import os, time, unittest
  import threading
  from test import support
  from test.support import threading_helper
  import warnings
label_desc: Use image node_id 5 for calling the ForkWait obj's underlying member method code with example usage: obj.test_wait() without return types