code: def test_system_concurrency_group(ray_start_regular_shared):
      @ray.remote
      class NormalActor:
          def block_forever(self):
              time.sleep(9999)
              return "never"
  
          def ping(self):
              return "pong"
  
      n = NormalActor.remote()
      n.block_forever.options(concurrency_group="_ray_system").remote()
      print(ray.get(n.ping.remote()))
  
file_path: ray/python/ray/tests/test_concurrency_group.py
imports: import asyncio
  import sys
  import threading
  import pytest
  import ray
  import time
  from ray._private.utils import get_or_create_event_loop
label_desc: Use image node_id 5 for calling a global function with example usage: test_system_concurrency_group(ray_start_regular_shared) and returns: str, str