code: def _blackhole(o):
      """Placeholder to be used in the benchmark to make sure runtime
      doesn't optimize out unused results"""
      pass
  
file_path: ray/python/ray/serve/_private/benchmarks/serialization/serialization_benchmark.py
imports: import asyncio
  import enum
  import pickle
  import time
  from typing import Any, Callable
  import click
  import msgpack
  from ray._private.serialization import SerializationContext
  from ray.cloudpickle import cloudpickle_fast
  from ray.serve._private.benchmarks.common import collect_profile_events, run_latency_benchmark
  from ray.serve._private.benchmarks.serialization.common import PayloadDataclass, PayloadPydantic
label_desc: Use image node_id 2 for calling a global function with example usage: _blackhole(o) without return types