enum MyError: Error {
    case failureA
    case failureB
}

func produceFailure() throws(MyError) -> Int {
    throw .failureB
}

func anotherFunction() {
    do throws(MyError) {
        let result = try produceFailure()
        //           `- error: errors thrown from here are not handled because the enclosing catch is not exhaustive
        print("Result:", result)
    } catch MyError.failureA {
        print("Failure A")
    } catch MyError.failureB {
        print("Failure B")
    }
}

anotherFunction()