code: def testGetAccumulateProcNull(self):
      obuf = [mkzeros(8), 0, MPI.INT]
      rbuf = [mkzeros(8), 0, MPI.INT]
      self.WIN.Fence()
      try:
          self.WIN.Get_accumulate(obuf, rbuf, MPI.PROC_NULL)
      except NotImplementedError:
          self.skipTest("mpi-win-get_accumulate")
      self.WIN.Fence()
  
imports: from mpi4py import MPI
  import mpiunittest
  import contextlib
  import arrayimpl
  import sys
label_desc: Use image node_id 12 for calling the BaseTestRMA obj's underlying member method code with example usage: obj.testGetAccumulateProcNull() without return types