[Koha] Extracting authorities from Biblios

Hello, We are currently using Koha 3.0.5 but we have not been using authorities and we would like to start using them. Is there a way to extract authorities from existing Biblios? Doing some searches on the Internet I saw some posts talking about an script "migration_tools/auth_from_biblio.pl" that doesn't seem to exist anymore in Koha 3. Was it deprecated? Is there a new way of extracting auths (populating them) from biblios? Regards, Toni