def METHOD_NAME(
    self,
    source_file: Path | str | None = None,
    bids_subject_id: str | None = None,
    subject_id: str | None = None,
) -> str | None:
    bids_database = self.ctx.bids_database
    if bids_subject_id is None:
        if source_file is not None:
            bids_path = bids_database.to_bids(source_file)
            assert bids_path is not None
            subject_id = bids_database.get_tag_value(bids_path, "subject")
        if subject_id is not None:
            bids_subject_id = format_like_bids(subject_id)
    if bids_subject_id is not None:
        return "single_subject_%s_wf" % bids_subject_id
    return None