buildExternalID :: ExternalID -> Builder
buildExternalID (SystemID sys)     = fromText "SYSTEM " <>
                                     quote (fromText sys)
buildExternalID :: ExternalID -> Builder
buildExternalID (SystemID sys)     = fromText "SYSTEM " <>
                                     quote (fromText sys)
buildExternalID (SystemID sys)     = fromText "SYSTEM " <>
                                     quote (fromText sys)