code: def get_free_tcp_port():
      tcp = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
      tcp.bind(("", 0))
      addr, port = tcp.getsockname()
      tcp.close()
      return str(port)
  
file_path: PARL/parl/utils/machine_info.py
imports: import os
  import platform
  import random
  import socket
  import subprocess
  from parl.utils import logger, _HAS_FLUID, _HAS_PADDLE, _IS_WINDOWS
label_desc: Use image node_id 5 for calling a global function with example usage: get_free_tcp_port() and returns: str