[HOW TO] walk over multiple node with manager?

Hi,
I am trying to understand if walking over multiple node is possible? 

```python
from snimpy.manager import Manager, load

load("some-mib")

with manager("host") as m:
  for index, value in m.portConfig.iteritems():
    print(index, value)
```

With this I can get portConfig (all index data), but if I want to walk to neighbour node how can I do it? 