code: def __str__(self):
      return os.environ.get(self._var, self._default)
  
imports: import collections
  import hashlib
  import json
  import os
  import random
  import string
  import subprocess
  import time
  from typing import TYPE_CHECKING, Any, Dict, List, Optional, Tuple
  import requests
  from ray_release.logger import logger
label_desc: Use image node_id 2 for calling the DeferredEnvVar obj's underlying member method code with example usage: obj.__str__() and returns: os