The Transport API in bzrlib provides URL based access to network resources.

   >>> import os
   >>> from bzrlib.osutils import getcwd, dirname
   >>> import bzrlib.transport as transport
   >>> root = transport.get_transport("file:///")
   >>>

Each Transport instance represents a single logical directory.

   >>> dir = transport.get_transport(".")
   >>> dir.base == getcwd() + '/'
   True

You can change directories via the clone method:

   >>> parent = dir.clone('..')
   >>> parent.base == (dirname(getcwd()).rstrip('/') + '/')
   True