'Verify that the final combination of on disk files complies with the
diskfile contract.
:param results: files that have been found and accepted
:returns: True if the file combination is compliant, False otherwise'

def _verify_ondisk_files(self, results, **kwargs):

    (data_file, meta_file, ts_file) = tuple([results[key] for key in ('data_file', 'meta_file', 'ts_file')])
    return (((data_file is None) and (meta_file is None) and (ts_file is None)) or ((ts_file is not None) and (data_file is None) and (meta_file is None)) or ((data_file is not None) and (ts_file is None)))
