It is a common need to find the grandparent or great-grandparent (etc.) of a given directory, which results in this:

>>> from os.path import dirname
>>> mydir = dirname(dirname(dirname(path)))

Could a "height" parameter be added to os.path.dirname so it becomes:

>>> def dirname(path, height=1):

Then we could have usage like:

>>> path = '/ggparent/gparent/parent/myfile.txt'
>>> from os.path import dirname

>>> dirname(path)
/ggparent/gparent/parent

>>> dirname(path, 2)
/ggparent/gparent

>>> dirname(path, 3)
/ggparent

Perhaps we should throw ValueErrors for invalid height values:

>>> dirname(path, 10)
ValueError

>>> dirname(path, -1)
ValueError

Perhaps a height of 0 should do nothing:

>>> dirname(path, 0)
/ggparent/gparent/parent/myfile.txt

I can supply patches, unit tests and docs if you like.