code: def _get_client_tag(
      client_id: Optional[str] = Query(None),
  ) -> Optional[str]:
      if client_id is None:
          return None
      return f"{client_id}_tag"
  
file_path: fastapi/tests/test_enforce_once_required_parameter.py
imports: from typing import Optional
  from fastapi import Depends, FastAPI, Query, status
  from fastapi.testclient import TestClient
label_desc: Use image node_id 2 for calling a global function with example usage: _get_client_tag(client_id) and returns: client_id, str, None