def relpath(path, start=os.path.curdir):
            """Return a relative version of a path"""
            from os.path import sep, curdir, join, abspath, commonprefix, \
                 pardir

            if not path:
                raise ValueError("no path specified")

            start_list = abspath(start).split(sep)
            path_list = abspath(path).split(sep)

            # Work out how much of the filepath is shared by start and path.
            i = len(commonprefix([start_list, path_list]))

            rel_list = [pardir] * (len(start_list)-i) + path_list[i:]
            if not rel_list:
                return curdir
            return join(*rel_list)