 			return [c] + cbs.map { (c : Callback) -> Callback in
 				switch c {
 				case let .afterFinalFailure(.counterexample, f):
-					return .afterTest(kind: .counterexample, f: f)
+					return .afterTest(kind: .counterexample, f)
 				default:
 					return c
 				}

/// to do with as it sees fit.
public enum Callback {
	/// A callback that is posted after a test case has completed.
	case afterTest(kind : CallbackKind, f : (CheckerState, TestResult) -> ())
	/// The callback is posted after all cases in the test have failed.
	case afterFinalFailure(kind : CallbackKind, f : (CheckerState, TestResult) -> ())
}

/// The type of callbacks SwiftCheck can dispatch.

				case .some(true):
					return Rose<TestResult>.pure(result2)
				case .some(false):
					let callbacks : [Callback] = [.afterFinalFailure(kind: .counterexample, { _ in return print("") })]
					return Rose<TestResult>.pure(TestResult(
						ok:            .some(false),
						expect:        true,
