code: def test_mp_is_worker():
      with invoker("foo", _worker_status, 2) as loop:
          res = list(loop.map(range(10)))
          assert all([w for (pid, w, mpw) in res])
          assert all([mpw for (pid, w, mpw) in res])
  
imports: import os
  import logging
  import multiprocessing
  import numpy
  import pytest
  from seedbank import root_seed
  from lenskit.util.parallel import invoker, proc_count, run_sp, is_worker, is_mp_worker
  from lenskit.util.test import set_env_var
  from lenskit.sharing import persist, SHM_AVAILABLE
  from pytest import mark, raises, approx
label_desc: Use image node_id 4 for calling a global function with example usage: test_mp_is_worker() without return types