code: def testUniverseSize(self):
      univsz = MPI.COMM_WORLD.Get_attr(MPI.UNIVERSE_SIZE)
      if univsz is not None:
          self.assertTrue(univsz == MPI.UNDEFINED or univsz >= 0)
  
imports: from mpi4py import MPI
  import mpiunittest
  import os
label_desc: Use image node_id 5 for calling the TestWorldAttrs obj's underlying member method code with example usage: obj.testUniverseSize() without return types