def _parseTrustRootPath(pathName):
    """
    Parse a string referring to a directory full of certificate authorities
    into a trust root.

    @param pathName: path name
    @type pathName: L{unicode} or L{bytes} or L{None}

    @return: L{None} or L{IOpenSSLTrustRoot}
    """
    if pathName is None:
        return None
    return _loadCAsFromDir(FilePath(pathName))

    Parse a string referring to a directory full of certificate authorities
    into a trust root.

    @param pathName: path name
    @type pathName: L{unicode} or L{bytes} or L{None}

    @return: L{None} or L{IOpenSSLTrustRoot}
    
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/endpoints.py