Return and args

I don't know if I missed somethign but I can't seem to fund a way to return value for the " only workers execute MPI code" mode. While the example seemed exciting, I can't seem to find a way to do a simple (pseudo code)

```
function do_stuff(args)
manager=MPIManager(np=np)
workers = addprocs(manager)
@mpi_do manager begin
result = do_mpi_stuff($args)
result = gather_on_root(results)
if comm is root
return result
end
end
end

myresult = do_stuff(a,b,c)
```

which makes it a bit useless since I can't get a result back.