code: def mysum_buf(a, b, dt):
      assert dt == MPI.INT
      assert len(a) == len(b)
      b[:] = mysum_obj(asarray("i", a), asarray("i", b))
  
imports: from mpi4py import MPI
  import mpiunittest
label_desc: Use image node_id 3 for calling a global function with example usage: mysum_buf(a, b, dt) without return types