code: def test_allreduce(self):
      rank = self.comm.rank
      size = self.comm.size
      msg = rank
      res = self.comm.allreduce(sendobj=msg)
      self.assertEqual(res, sum(range(size)))
  
imports: from mpi4py import MPI
  import unittest
  import sys, os
  from reductions import Intracomm
label_desc: Use image node_id 6 for calling the BaseTest obj's underlying member method code with example usage: obj.test_allreduce() without return types