code: def _sp_matmul_p(a1, a2, *, method=None, fail=False):
      _log.info("in worker process")
      return persist(a1 @ a2, method=method).transfer()
  
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 11 for calling a global function with example usage: _sp_matmul_p(a1, a2) and returns: persist