code: def tech_alias(self) -> Optional[List[UnitTypeId]]:
          
          """ 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
docs: Building tech equality, e.g. OrbitalCommand is the same as CommandCenter