code: def time_created_str(self):
      return time_msecs_str(self.time_created)
  
imports: import base64
  import json
  import logging
  import secrets
  from typing import Dict, Optional
  import aiohttp
  from gear import Database, transaction
  from hailtop import httpx
  from hailtop.humanizex import naturaldelta_msec
  from hailtop.utils import retry_transient_errors, time_msecs, time_msecs_str
  from ..cloud.utils import instance_config_from_config_dict
  from ..globals import INSTANCE_VERSION
  from ..instance_config import InstanceConfig
label_desc: Use image node_id 13 for calling the Instance obj's underlying member method code with example usage: obj.time_created_str() and returns: time_msecs_str