(literal: Aux[Input, Aux[OutputData, OutputDelta]]).forward
(literal: StringAdd).self
(literal: StringFormat).self
(literal: ArrowAssoc[Literal[Data0]]).x
(Since version 2.10.0) Use leftOfArrow instead
(literal: Ensuring[Literal[Data0]]).x
(Since version 2.10.0) Use resultOfEnsuring instead