formatting: Remove segment parts, you can use template tags instead. Segment parts were used to switch formatters insides a given content segment, but that's also achievable with template tags like `pcformat` in Jinja to some degree. It's not totally the same but removing it simplifies the code and improves performance.

import os


def slashfix(path):
    if path is None:
        return None
    if isinstance(path, str):
        return path.replace('/', os.sep)
    fixed = []
    for p in path:
        fixed.append(p.replace('/', os.sep))
    return fixed