def index(meta_tree, field_name, *key_trail):
meta_data = get_metadata(meta_tree, *key_trail)
val = meta_data.get(field_name)
return helpers.listify(val)
def ret(meta_tree, *key_trail):
metadata = metatree.get_metadata(meta_tree, *key_trail)
return metadata is not None and field_name in metadata