class_docstr: A class to load, modify, and display the StreamAlertCLI Config
docstr: Return list of cluster configuration keys
docstr_tok: ["Return","list","of","cluster","configuration","keys"]
code: def clusters(self):
      """Return list of cluster configuration keys"""
      return list(self.config["clusters"].keys())
  
imports: import json
  import os
  import re
  import shutil
  import string
  import tempfile
  from streamalert.apps import StreamAlertApp
  from streamalert.shared import CLUSTERED_FUNCTIONS, config, metrics
  from streamalert.shared.logger import get_logger
  from streamalert_cli.terraform import TERRAFORM_FILES_PATH
  from streamalert_cli.apps.helpers import save_app_auth_info
  from streamalert_cli.helpers import continue_prompt
label_desc: Use image node_id 7 for calling the CLIConfig obj's underlying member method code with example usage: obj.clusters() and returns: list