code: def test_deployment_function_node_build(serve_instance):
      @serve.deployment
      class Forward:
          def __init__(self, handle: DeploymentHandle):
              self.handle = handle
  
          async def __call__(self, *args, **kwargs):
              return await self.handle.remote()
  
      @serve.deployment
      def no_op():
          return "No-op"
  
      app = Forward.bind(Forward.bind(Forward.bind(no_op.bind())))
  
      serve.run(app)
      assert requests.get("http://localhost:8000/").text == "No-op"
  
file_path: ray/python/ray/serve/tests/test_deployment_graph_build.py
imports: import pytest
  import requests
  import ray
  from ray import serve
  from ray.dag.utils import _DAGNodeNameGenerator
  from ray.serve._private import api
  from ray.serve._private.deployment_graph_build import extract_deployments_from_serve_dag, transform_ray_dag_to_serve_dag
  from ray.serve.handle import DeploymentHandle
  from ray.serve.tests.common.test_modules import NESTED_HANDLE_KEY, Combine, Model
label_desc: Use image node_id 8 for calling a global function with example usage: test_deployment_function_node_build(serve_instance) and returns: str, unknown