Automatically implements From for each type in an aggregate type enum.
This macro treats the supplied enum as an aggregate constraint checker. As such, it implements the From
trait for eah of the inner types. Then it implements the ConstraintChecker trait for this type for this
enum by delegating to an inner type.
This macro treats the supplied enum as an aggregate verifier. As such, it implements the From
trait for eah of the inner types. Then it implements the Verifier trait for this type for this
enum by delegating to an inner type.