def _find_metadata(file_alf):
    """
    Loof for an existing meta-data file for an alf_file
    :param file_alf: PurePath of existing alf file
    :return: PurePath of meta-data if exists
    """
    ns, obj = file_alf.name.split('.')[:2]
    meta_data_file = list(file_alf.parent.glob(f'{ns}.{obj}*.metadata*.json'))
    if meta_data_file:
        return meta_data_file[0]
