private
    fun <T : Any> valueCarriedBy(isolatedAction: TestableIsolatedAction<T>): T {
        lateinit var value: T
        isolatedAction.execute {
            value = it
        }
        return value
    }

    private
    fun <T> roundtripOf(action: TestableIsolatedAction<T>): TestableIsolatedAction<T> =
        deserialize(serialize(action))

    private