code: def index():
      """Default handler for the test bench."""
      return "OK"
  
imports: import argparse
  import error_response
  import flask
  import gcs_bucket
  import gcs_object
  import json
  import os
  import re
  import testbench_utils
  import time
  import sys
  from werkzeug import serving
  from werkzeug.middleware.dispatcher import DispatcherMiddleware
label_desc: Use image node_id 1 for calling a global function with example usage: index() and returns: str