code: def testAccumulateProcNullSum(self):
      rank = self.COMM.Get_rank()
      zeros = mkzeros(8)
      with win_lock(self.WIN, rank):
          r = self.WIN.Raccumulate(
              [zeros, MPI.INT], MPI.PROC_NULL, None, MPI.SUM
          )
          r.Wait()
          r = self.WIN.Raccumulate(
              [None, MPI.INT], MPI.PROC_NULL, None, MPI.SUM
          )
          r.Wait()
  
imports: from mpi4py import MPI
  import mpiunittest
  import contextlib
  import arrayimpl
label_desc: Use image node_id 9 for calling the BaseTestRMA obj's underlying member method code with example usage: obj.testAccumulateProcNullSum() without return types