code: def testIRecvAndISSend(self):
      comm = self.COMM
      rank = comm.Get_rank()
      for smess in messages:
          src = dst = rank
          req1 = comm.irecv(None, src, 1)
          req2 = comm.irecv(None, src, 2)
          req3 = comm.irecv(None, src, 3)
          req4 = comm.issend(smess, dst, 3)
          req5 = comm.issend(smess, dst, 2)
          req6 = comm.issend(smess, dst, 1)
          MPI.Request.waitall([req4, req5, req6])
          self.assertEqual(smess, req3.wait())
          self.assertEqual(smess, req2.wait())
          self.assertEqual(smess, req1.wait())
          comm.issend(smess, MPI.PROC_NULL, 3).wait()
  
imports: from mpi4py import MPI
  import mpiunittest
  import threading
  import warnings
  import sys
label_desc: Use image node_id 13 for calling the BaseTestP2PObj obj's underlying member method code with example usage: obj.testIRecvAndISSend() without return types