code: def setUp(self):
      self.port = get_free_tcp_port()
      self.ctx = mp.get_context()
      self.sub_process = []
      self.sub_process_type = []
      self.worker_process = []
  
imports: import unittest
  from parl.utils import get_free_tcp_port
  from parl.utils import is_port_available
  from parl.utils import logger
  import multiprocessing
  from parl.remote.master import Master
  from parl.remote.worker import Worker
  from parl.remote.client import disconnect
  from parl.remote import remote_constants
  import time
  import os
  import signal
  import psutil
  import subprocess
label_desc: Use image node_id 1 for calling the XparlTestCase obj's underlying member method code with example usage: obj.setUp() without return types