Iterate over the entire path one part at a time.

pathcrement.py

#!/usr/bin/env python3
import os

mainpath = 'foo/bar/baz/qux/garple/sux/'

def incrementally_joined(parts):
    full = ''
    for p in parts:
        full += p + os.sep
        yield full

def pathcrement(mypath):
    #strip off any os.sep on either end of the path, and split into an array
    return os.path.splitdrive(mypath)[1].lstrip(os.sep).rstrip(os.sep).split(os.sep)

for path in incrementally_joined(pathcrement(mainpath)):
    print(path)