code: def continuation(dag_node: "DAGNode") -> Union["DAGNode", Any]:
      """Converts a DAG into a continuation.
  
      The result depends on the context. If it is inside a workflow, it
      returns a workflow; otherwise it executes and get the result of
      the DAG.
  
      Args:
          dag_node: The DAG to be converted.
      """
      from ray.workflow.workflow_context import in_workflow_execution
  
      if not isinstance(dag_node, DAGNode):
          raise TypeError("Input should be a DAG.")
  
      if in_workflow_execution():
          return dag_node
      return ray.get(dag_node.execute())
  
imports: import functools
  import logging
  import tempfile
  from typing import Dict, Set, List, Tuple, Union, Optional, Any
  import time
  import uuid
  from pathlib import Path
  import ray
  from ray.dag import DAGNode
  from ray.dag.input_node import DAGInputData
  from ray.remote_function import RemoteFunction
  from ray.workflow.common import WorkflowStatus, Event, asyncio_run, validate_user_metadata
  from ray.workflow import serialization, workflow_access, workflow_context
  from ray.workflow.event_listener import EventListener, EventListenerType, TimerListener
  from ray.workflow.workflow_storage import WorkflowStorage
  from ray.workflow.workflow_state_from_dag import workflow_state_from_dag
  from ray.util.annotations import PublicAPI
  from ray._private.usage import usage_lib
label_desc: Use image node_id 18 for calling a global function with example usage: continuation(dag_node) and returns: ray, dag_node