code: def __reduce__(self):
      return _resolve_workflow_refs, (self._index,)
  
file_path: ray/python/ray/workflow/serialization_context.py
imports: import contextlib
  from typing import List, Any, Dict
  from ray.util.serialization import register_serializer, deregister_serializer
  from ray.workflow.common import WorkflowRef
label_desc: Use image node_id 2 for calling the _KeepWorkflowRefs obj's underlying member method code with example usage: obj.__reduce__() and returns: _resolve_workflow_refs,  self