code: def _pick_unused_port():
      """Returns a free port on localhost."""
  
      for family in (socket.AF_INET6, socket.AF_INET):
          try:
              sock = socket.socket(family, socket.SOCK_STREAM)
              sock.bind(
                  ("", 0)
              )  # Passing port '0' binds to a free port on localhost.
              port = sock.getsockname()[1]
              sock.close()
              return port
          except socket.error:
              continue
      raise socket.error
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import collections
  import copy
  import itertools
  import json
  import os
  import shutil
  import socket
  import subprocess
  import sys
  import time
  from absl import flags
  from absl import logging
  from absl.testing import parameterized
  from adanet import tf_compat
  from adanet.core.timer import _CountDownTimer
  import tensorflow.compat.v2
label_desc: Use image node_id 2 for calling a global function with example usage: _pick_unused_port() and returns: port