code: def unused_tcp_port():
      s = socket.socket()
      s.bind(("127.0.0.1", 0))
      port = s.getsockname()[1]
      s.close()
      return port
  
file_path: pystan/stan/common.py
imports: import socket
  import typing
  import aiohttp
  import aiohttp.web
  import httpstan.app
  import simdjson
label_desc: Use image node_id 1 for calling a global function with example usage: unused_tcp_port() and returns: port