from mpi4py import MPI

comm = MPI.COMM_WORLD
rank = comm.Get_rank()
size = comm.Get_size()

target = (rank + 1) % size
source = (rank - 1) % size

#if rank == 0:
data = rank
comm.send(data, dest=target, tag=11)
#elif rank == 1:
data = comm.recv(source=source, tag=11)

print("Rank: " + str(rank) + " Data: " + str(data))