(unitFunctors: StringAdd).self
(unitFunctors: StringFormat).self
(unitFunctors: ArrowAssoc[UnitFunctors]).x
(Since version 2.10.0) Use leftOfArrow instead
(unitFunctors: Ensuring[UnitFunctors]).x
(Since version 2.10.0) Use resultOfEnsuring instead
One of the 'unit' definitions must be overridden in concrete subclasses