So, now that we have the ability to resume at a give point by using the label, we need to modify the other suspending functions that are called from getUserSummary(), so that they also receive CoroutineImpl. Let's say that we, as the compiler, have modified the fetchProfile() and validateTerms() functions so that they received a Continuation<Any?>—just like we did for getUserSummary()—and called doResume() upon the completion of their execution. Then we could invoke them like this:

when(state.label) {
    0 -> { // Label 0 -> first execution
        logger.log("fetching summary of $id")
        fetchProfile(id, sm)
        return
    }
    1 -> { // label 1 -> resuming
        calculateAge(profile.dateOfBirth)
        validateTerms(profile.country, age, sm)
        return
    }
    2 -> // label 2 -> resuming and terminating
        UserSummary(profile, age, terms)
}

By having both fetchProfile() and validateTerms() call the continuation that they receive whenever they finish their execution, we are having them call the continuation that we implemented in getUserSummary(), thus resuming its execution.