How to walk up parent directories?

[Snorri H]

On May 4, 5:04 am, Matthew Wilson <m... at tplus1.com> wrote:
> Is there already a tool in the standard library to let me walk up from a
> subdirectory to the top of my file system?


Never seen such a standard tool, yet it can be implemented in a way
like this

def walkup(path):
    aux = path.rsplit('/')
    while aux != ['']:
        yield reduce(lambda x,y:x+'/'+y,aux)
        aux.pop()
    yield '/'

Maybe this is not the best way to ascend directories, but it seems to
work.