code: def test_get_app_handle_within_deployment_async(serve_instance):
      @serve.deployment()
      class a:
          def __init__(self, handle):
              self.handle = handle
  
          def __call__(self, val: int):
              return val + 2
  
      @serve.deployment()
      class b:
          def __call__(self, val: int):
              return val
  
      @serve.deployment
      async def f(val):
          handle = serve.get_app_handle(SERVE_DEFAULT_APP_NAME)
          result = await handle.remote(val)
          return f"The answer is {result}"
  
      serve.run(a.bind(b.bind()), route_prefix="/math")
      serve.run(f.bind(), name="call")
  
      handle = serve.get_app_handle("call")
      assert handle.remote(7).result() == "The answer is 9"
  
imports: import asyncio
  import os
  import sys
  from typing import Dict, Optional
  import pytest
  import requests
  import starlette.responses
  from fastapi import FastAPI
  import ray
  from ray import serve
  from ray._private.pydantic_compat import BaseModel, ValidationError
  from ray._private.test_utils import SignalActor, wait_for_condition
  from ray.serve._private.api import call_app_builder_with_args_if_necessary
  from ray.serve._private.common import DeploymentID
  from ray.serve._private.constants import SERVE_DEFAULT_APP_NAME
  from ray.serve.deployment import Application
  from ray.serve.exceptions import RayServeException
  from ray.serve.handle import DeploymentHandle, RayServeHandle
label_desc: Use image node_id 32 for calling a global function with example usage: test_get_app_handle_within_deployment_async(serve_instance) and returns: str, result, unknown, val