code: def transform_ray_dag_to_serve_dag(
      dag_node: DAGNode,
      node_name_generator: _DAGNodeNameGenerator,
      app_name: str,
  ):
      """
      Transform a Ray DAG to a Serve DAG. Map ClassNode to DeploymentNode with
      ray decorated body passed in.
      """
      if isinstance(dag_node, ClassNode):
          deployment_name = node_name_generator.get_node_name(dag_node)
  
          # Deployment can be passed into other DAGNodes as init args. This is
          # supported pattern in ray DAG that user can instantiate and pass class
          # instances as init args to others.
  
          # However in ray serve we send init args via .remote() that requires
          # pickling, and all DAGNode types are not picklable by design.
  
          # Thus we need convert all DeploymentNode used in init args into
          # deployment handles (executable and picklable) in ray serve DAG to make
          # serve DAG end to end executable.
          def replace_with_handle(node):
              if isinstance(node, DeploymentNode) or isinstance(
                  node, DeploymentFunctionNode
              ):
                  if RAY_SERVE_ENABLE_NEW_HANDLE_API:
                      return DeploymentHandle(
                          node._deployment.name, app_name, sync=False
                      )
                  else:
                      return RayServeHandle(
                          node._deployment.name, app_name, sync=False
                      )
              elif isinstance(node, DeploymentExecutorNode):
                  return node._deployment_handle
  
          (
              replaced_deployment_init_args,
              replaced_deployment_init_kwargs,
          ) = dag_node.apply_functional(
              [dag_node.get_args(), dag_node.get_kwargs()],
              predictate_fn=lambda node: isinstance(
                  node,
                  # We need to match and replace all DAGNodes even though they
                  # could be None, because no DAGNode replacement should run into
                  # re-resolved child DAGNodes, otherwise with KeyError
                  (
                      DeploymentNode,
                      DeploymentFunctionNode,
                      DeploymentExecutorNode,
                      DeploymentFunctionExecutorNode,
                  ),
              ),
              apply_fn=replace_with_handle,
          )
  
          # ClassNode is created via bind on serve.deployment decorated class
          # with no serve specific configs.
          deployment_schema: DeploymentSchema = (
              dag_node._bound_other_args_to_resolve["deployment_schema"]
          )
  
          deployment_shell: Deployment = schema_to_deployment(
              deployment_schema
          )
  
          # Prefer user specified name to override the generated one.
          if (
              inspect.isclass(dag_node._body)
              and deployment_shell.name != dag_node._body.__name__
          ):
              deployment_name = deployment_shell.name
  
          # Set the route prefix, prefer the one user supplied,
          # otherwise set it to /deployment_name
          if (
              deployment_shell.route_prefix is None
              or deployment_shell.route_prefix
              != f"/{deployment_shell.name}"
          ):
              route_prefix = deployment_shell.route_prefix
          else:
              route_prefix = f"/{deployment_name}"
  
          deployment = deployment_shell.options(
              func_or_class=dag_node._body,
              name=deployment_name,
              route_prefix=route_prefix,
              _init_args=replaced_deployment_init_args,
              _init_kwargs=replaced_deployment_init_kwargs,
              _internal=True,
          )
  
          return DeploymentNode(
              deployment,
              app_name,
              dag_node.get_args(),
              dag_node.get_kwargs(),
              dag_node.get_options(),
              other_args_to_resolve=dag_node.get_other_args_to_resolve(),
          )
      elif isinstance(
          dag_node,
          FunctionNode
          # TODO (jiaodong): We do not convert ray function to deployment function
          # yet, revisit this later
      ) and dag_node.get_other_args_to_resolve().get(
          "is_from_serve_deployment"
      ):
          deployment_name = node_name_generator.get_node_name(dag_node)
  
          other_args_to_resolve = dag_node.get_other_args_to_resolve()
          if "return" in dag_node._body.__annotations__:
              other_args_to_resolve[
                  "result_type_string"
              ] = type_to_string(
                  dag_node._body.__annotations__["return"]
              )
  
          # Set the deployment name if the user provides.
          if (
              "deployment_schema"
              in dag_node._bound_other_args_to_resolve
          ):
              schema = dag_node._bound_other_args_to_resolve[
                  "deployment_schema"
              ]
              if (
                  inspect.isfunction(dag_node._body)
                  and schema.name != dag_node._body.__name__
              ):
                  deployment_name = schema.name
  
          return DeploymentFunctionNode(
              dag_node._body,
              deployment_name,
              app_name,
              dag_node.get_args(),
              dag_node.get_kwargs(),
              dag_node.get_options(),
              other_args_to_resolve=other_args_to_resolve,
          )
      else:
          # TODO: (jiaodong) Support FunctionNode or leave it as ray task
          return dag_node
  
imports: import inspect
  from collections import OrderedDict
  from typing import List
  from ray.dag import ClassNode, DAGNode
  from ray.dag.function_node import FunctionNode
  from ray.dag.utils import _DAGNodeNameGenerator
  from ray.experimental.gradio_utils import type_to_string
  from ray.serve._private.constants import RAY_SERVE_ENABLE_NEW_HANDLE_API, SERVE_DEFAULT_APP_NAME
  from ray.serve._private.deployment_executor_node import DeploymentExecutorNode
  from ray.serve._private.deployment_function_executor_node import DeploymentFunctionExecutorNode
  from ray.serve._private.deployment_function_node import DeploymentFunctionNode
  from ray.serve._private.deployment_node import DeploymentNode
  from ray.serve.deployment import Deployment, schema_to_deployment
  from ray.serve.handle import DeploymentHandle, RayServeHandle
  from ray.serve.schema import DeploymentSchema
label_desc: Use image node_id 3 for calling a global function with example usage: transform_ray_dag_to_serve_dag(dag_node, node_name_generator, app_name) and returns: DeploymentNode, DeploymentFunctionNode, dag_node, DeploymentHandle, RayServeHandle, node