code: def testAlltoall(self):
      size = self.COMM.Get_size()
      rank = self.COMM.Get_rank()
      for smess in messages + [messages]:
          rmess = self.COMM.alltoall([smess] * size)
          self.assertEqual(rmess, [smess] * size)
  
imports: from mpi4py import MPI
  import mpiunittest
  from functools import reduce
label_desc: Use image node_id 6 for calling the BaseTestCCOObj obj's underlying member method code with example usage: obj.testAlltoall() without return types