equivalent of Ruby's Pathname?

[Phlip]

Pythonistas:

Yes, calling os.path.walk() and os.path.join() all the time on raw
strings is fun, but I seem to recall from my Ruby days a class called
Pathname, which presented an object that behaved like a string at
need, and like a filesystem path at need. path + 'folder' would
call .join() and insert the / correctly, for example.

What's the best equivalent in Python-land?

--
  Phlip