def METHOD_NAME(self, data: object, **kwargs):
    # copy fields from root object into the 'conf'
    conf = data.conf or {}
    for field_name, _ in CONF_KEY_MAP.items():
        value = data.__getattribute__(field_name)
        if value is not None:
            conf[field_name] = value
    data.__setattr__("conf", conf)
    return data