code: def compose_customized_metric_key(
      namespace: str,
      metric_name: str,
      description: Optional[str] = None,
  ) -> str:
      r"""Get the metric key. The input are unrestricted (string) namespace and
      metric_name. This API should only be used by compose_metric_key() and
      state metrics as the keys of state metrics are unknown.
      """
      return f"{namespace}|{metric_name}{description or ''}"
  
imports: from enum import Enum
  from typing import Optional
label_desc: Use image node_id 3 for calling a global function with example usage: compose_customized_metric_key(namespace, metric_name, description) and returns: namespace, str, metric_name, unknown