code: def test_arg_processes(self):
      with self.assertRaises(ValueError):
          self.Pool(-1)
      with self.assertRaises(ValueError):
          self.Pool(0)
  
imports: from mpi4py import MPI
  import mpi4py.util.pool
  import concurrent.futures
  import itertools
  import functools
  import warnings
  import unittest
  import time
  import sys
  import os
label_desc: Use image node_id 21 for calling the BaseTestPool obj's underlying member method code with example usage: obj.test_arg_processes() without return types