code: def testCollectivesBlock(self):
      comm = self.COMM
      comm.Bcast(self.null_b)
      comm.Gather(self.null_b, self.null_b)
      comm.Scatter(self.null_b, self.null_b)
      comm.Allgather(self.null_b, self.null_b)
      comm.Alltoall(self.null_b, self.null_b)
  
file_path: mpi4py/test/test_msgzero.py
imports: from mpi4py import MPI
  import mpiunittest
label_desc: Use image node_id 2 for calling the BaseTestMessageZero obj's underlying member method code with example usage: obj.testCollectivesBlock() without return types