docstr: replace known config variable occurrences in the input string
  does not replace variables with undefined or empty strings
docstr_tok: ["replace","known","config","variable","occurrences","in","the","input","string","does","not","replace","variables","with","undefined","or","empty","strings"]
code: def _replace_config_variables(
      self, string: str, node_id: str, cluster_name: str, region: str
  ) -> str:
      """
      replace known config variable occurrences in the input string
      does not replace variables with undefined or empty strings
      """
  
      if node_id:
          string = string.replace("{instance_id}", node_id)
      if cluster_name:
          string = string.replace("{cluster_name}", cluster_name)
      if region:
          string = string.replace("{region}", region)
      return string
  
imports: import copy
  import hashlib
  import json
  import logging
  import os
  import time
  from enum import Enum
  from typing import Any, Callable, Dict, List, Union
  import botocore
  from ray.autoscaler._private.aws.utils import client_cache, resource_cache
  from ray.autoscaler.tags import NODE_KIND_HEAD, TAG_RAY_CLUSTER_NAME, TAG_RAY_NODE_KIND
label_desc: Use image node_id 9 for calling the CloudwatchHelper obj's underlying member method code with example usage: obj._replace_config_variables(string, node_id, cluster_name, region) and returns: string