suspendAsync1.kt

suspend fun saveUsername(username: String) {

    val result = suspendAsync(StorageService.getInstance()::saveUsername, username)
    handleResult(result)
}

suspend fun <Input, Output> suspendAsync(function: (Input, (Output) -> Unit) -> Unit,
                                         input: Input) =  suspendCoroutine<Output> { continuation ->
    function(input) { output ->
        continuation.resume(output)
    }
}