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

   >>> import os
   >>> import sys
   >>> from bzrlib.osutils import getcwd, dirname
   >>> from bzrlib.urlutils import local_path_from_url
   >>> import bzrlib.transport as transport
   >>> if sys.platform == 'win32':
   ...     root = transport.get_transport_from_url('file:///C:/')
   ... else:
   ...     root = transport.get_transport_from_url('file:///')
   >>>

Each Transport instance represents a single logical directory.

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

You can change directories via the clone method:

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