code: def test_parallel_func(n_jobs):
      """Test Parallel wrapping."""
      joblib = pytest.importorskip("joblib")
      if os.getenv("MNE_FORCE_SERIAL", "").lower() in ("true", "1"):
          pytest.skip("MNE_FORCE_SERIAL cannot be set")
  
      def fun(x):
          return x * 2
  
      if isinstance(n_jobs, str):
          backend, n_jobs = n_jobs.split()
          n_jobs = want_jobs = int(n_jobs)
          try:
              func = joblib.parallel_config
          except AttributeError:
              # joblib < 1.3
              func = joblib.parallel_backend
          ctx = func(backend, n_jobs=n_jobs)
          n_jobs = None
      else:
          ctx = nullcontext()
          if n_jobs is not None and n_jobs < 0:
              want_jobs = multiprocessing.cpu_count() + 1 + n_jobs
          else:
              want_jobs = 1
      with ctx:
          parallel, p_fun, got_jobs = parallel_func(
              fun, n_jobs, verbose="debug"
          )
      assert got_jobs == want_jobs
  
imports: import multiprocessing
  import os
  from contextlib import nullcontext
  import pytest
  from mne.parallel import parallel_func
label_desc: Use image node_id 1 for calling a global function with example usage: test_parallel_func(n_jobs) and returns: unknown