code: def test_concurrent_future(ray_start_regular_shared):
      ref = ray.put(1)
  
      fut = ref.future()
      assert isinstance(fut, concurrent.futures.Future)
      wait_for_condition(lambda: fut.done())
  
      global_result = None
  
      def cb(fut):
          nonlocal global_result
          global_result = fut.result()
  
      fut.add_done_callback(cb)
      assert global_result == 1
      assert fut.result() == 1
  
imports: import asyncio
  import concurrent.futures
  import sys
  import time
  import numpy
  import pytest
  import ray
  from ray._private.async_compat import is_async_func
  from ray._private.test_utils import wait_for_condition
  from ray._private.utils import get_or_create_event_loop, run_background_task, background_tasks
label_desc: Use image node_id 10 for calling a global function with example usage: test_concurrent_future(ray_start_regular_shared) without return types