code: def test_pool_one_task(start_method):
      groups = [MockGroup.from_callback(simple_callback)]
      with create_pool(
          groups,
          keep_alive_queue_size=1,
          num_workers=1,
          start_method=start_method,
      ) as pool:
          pids = get_pids(pool)
          pid = pids[0]
          tasks = [(SampleInfo(0, 0, 0, 0),)]
          work_batch = TaskArgs.make_sample(SampleRange(0, 1, 0, 0))
          pool.schedule_batch(context_i=0, work_batch=work_batch)
          batch = pool.receive_batch(context_i=0)
          for task, sample in zip(tasks, batch):
              np.testing.assert_array_equal(answer(pid, *task), sample)
  
imports: from nvidia.dali._multiproc.pool import WorkerPool
  from nvidia.dali._multiproc.messages import TaskArgs, SampleRange
  from contextlib import closing
  from nvidia.dali._utils.external_source_impl import get_callback_from_source
  from nvidia.dali.types import SampleInfo
  from functools import wraps
  import numpy
  import os
  from nose.tools import with_setup
  from nose_utils import raises
  from test_pool_utils import capture_processes, setup_function, teardown_function
label_desc: Use image node_id 8 for calling a global function with example usage: test_pool_one_task(start_method) without return types