code: def testScatter(self):
      size = self.COMM.Get_size()
      rank = self.COMM.Get_rank()
      for array, typecode in arrayimpl.loop():
          for root in range(size):
              check = arrayimpl.scalar(root)
              rbuf = array(-1, typecode, size)
              if rank == root:
                  sbuf = array(root, typecode, (size, size))
              else:
                  sbuf = array([], typecode)
              self.COMM.Iscatter(
                  sbuf.as_mpi(), rbuf.as_mpi(), root=root
              ).Wait()
              for value in rbuf:
                  self.assertEqual(value, check)
  
imports: from mpi4py import MPI
  import mpiunittest
  import arrayimpl
  from functools import reduce
label_desc: Use image node_id 4 for calling the BaseTestCCOBuf obj's underlying member method code with example usage: obj.testScatter() without return types