code: def add_master(self, device=remote_constants.CPU):
      p_master = self.ctx.Process(
          target=self._create_master, args=(device,)
      )
      p_master.start()
      self.sub_process.append(p_master)
      self.sub_process_type.append("master")
      while is_port_available(self.port):
          logger.info("Master[localhost:{}] starting".format(self.port))
          time.sleep(1)
      logger.info("Master[localhost:{}] started".format(self.port))
      time.sleep(10)
  
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 5 for calling the XparlTestCase obj's underlying member method code with example usage: obj.add_master(device) without return types