class_docstr: A class to load, modify, and display the StreamAlertCLI Config
code: def _clusters_with_metrics_enabled(self, function):
      function_config = "{}_config".format(function)
      return {
          cluster
          for cluster, cluster_config in self.config["clusters"].items()
          if (
              self.config["clusters"][cluster][function_config].get(
                  "enable_custom_metrics"
              )
          )
      }
  
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 17 for calling the CLIConfig obj's underlying member method code with example usage: obj._clusters_with_metrics_enabled(function) and returns: unknown