code: def prefix_application(self, app, service, **kwargs):
      from aiohttp import web  # pylint: disable=import-outside-toplevel
  
      base_path = self.base_path(service)
      if not base_path:
          return app
  
      root_routes = web.RouteTableDef()
  
      @root_routes.get("/healthcheck")
      async def get_healthcheck(_):
          return web.Response()
  
      @root_routes.get("/metrics")
      async def get_metrics(_):
          raise web.HTTPFound(location=f"{base_path}/metrics")
  
      root_app = web.Application(**kwargs)
      root_app.add_routes(root_routes)
      root_app.add_subapp(base_path, app)
  
      log.info(f"serving paths at {base_path}")
      return root_app
  
imports: from typing import Dict, Optional, TypeVar, Union
  import os
  import json
  import logging
  from ..utils import first_extant_file
  from .user_config import get_user_config
label_desc: Use image node_id 16 for calling the DeployConfig obj's underlying member method code with example usage: obj.prefix_application(app, service) and returns: root_app, app, web