features = [(ftype, fname) for ftype, fname in FeatureParser(features)(self)]
ftrs = [(ftype, fname) for ftype, fname in features if not ftype.is_meta()]
meta = list(set([(ftype, ...) for ftype, _ in features if ftype.is_meta()]))
features = ftrs + meta
file_saver_list = self._get_save_file_list("", "", features, file_format, compress_level)
After Change
features = list(FeatureParser(features)(self))
ftrs = {(ftype, fname) for ftype, fname in features if not ftype.is_meta()}
meta = {(ftype, ...) for ftype, _ in features if ftype.is_meta()}
features = list(ftrs | meta)
file_saver_list = self._get_save_file_list("", "", features, file_format, compress_level)