Building tech equality, e.g. OrbitalCommand is the same as CommandCenter

def tech_alias(self) -> Optional[List[UnitTypeId]]:
        """ Building tech equality, e.g. OrbitalCommand is the same as CommandCenter """
        """ Building tech equality, e.g. Hive is the same as Lair and Hatchery """
        return_list = []
        for tech_alias in self._proto.tech_alias:
            if tech_alias in self._game_data.units:
                return_list.append(UnitTypeId(tech_alias))
        """ For Hive, this returns [UnitTypeId.Hatchery, UnitTypeId.Lair] """
        """ For SCV, this returns None """
        if return_list:
            return return_list
        return None