code: def ringtest(comm):
      size = 1
      loop = 1
      skip = 0
  
      lib.MPI_Barrier(comm)
      elapsed = ring(comm, size, loop, skip)
  
      size_p = ffi.new("int*")
      rank_p = ffi.new("int*")
      lib.MPI_Comm_size(comm, size_p)
      lib.MPI_Comm_rank(comm, rank_p)
      comm_size = size_p[0]
      comm_rank = rank_p[0]
  
      if comm_rank == 0:
          print(
              "time for %d loops = %g seconds (%d processes, %d bytes)"
              % (loop, elapsed, comm_size, size)
          )
  
imports: from libmpi import ffi, lib
label_desc: Use image node_id 2 for calling a global function with example usage: ringtest(comm) without return types