mets caching: use fileGrp cache for OcrdMets.file_groups
@@ -210,8 +210,8 @@ class OcrdMets(OcrdXmlDocument):
"""
# WARNING: Actually we cannot return strings in place of elements!
- #if self._cache_flag:
- # return self._file_cache.keys()
+ if self._cache_flag:
+ return list(self._file_cache.keys())
return [el.get('USE') for el in self._tree.getroot().findall('.//mets:fileGrp', NS)]
