gistfile1.txt

abstract class UseCase<out Type, in Params> where Type : Any? {

    abstract suspend fun run(params: Params): Either<Failure, Type>

    suspend operator fun invoke(params: Params, coroutinesDispatcherProvider: CoroutinesDispatcherProvider, onResult: (Either<Failure, Type>) -> Unit = {}) {
        val result = run(params)
        withContext(coroutinesDispatcherProvider.main) {
            onResult(result)
        }
    }

    suspend operator fun invoke(coroutinesDispatcherProvider: CoroutinesDispatcherProvider, onResult: (Either<Failure, Type>) -> Unit = {}) {
        val result = run(None() as Params)
        withContext(coroutinesDispatcherProvider.main) {
            onResult(result)
        }
    }

    class None
}

gistfile2.txt

class NewUkSignInViewModel(
        val getSupportedCountriesUseCase: GetSupportedCountriesUseCase,
        val coroutinesDispatcherProvider: CoroutinesDispatcherProvider) : BaseViewModel(), CoroutineScope {

    private val executionJob: Job  by lazy { Job() }

    override val coroutineContext: CoroutineContext by lazy {
        Dispatchers.Default + executionJob
    }

    val countriesAvailableNames: MutableLiveData<String> = mutableLiveData()
    val errorEvent: SingleLiveData<String> = singleLiveData()

    init {
        loadCountries()
    }
    
    fun loadCountries(){

        this.launch {
            getSupportedCountriesUseCase(coroutinesDispatcherProvider) {
                it.fold(::showError, ::showCountries)
            }
        }
    }

    private fun showError(failure: Failure){
        print("error")
        errorEvent.value = failure.toString()
    }

    private fun showCountries(result: List<Country>) {
        val countriesViewDataList = result.map {
            it.id
        }.toString()
        print("1 success")
        countriesAvailableNames.value = countriesViewDataList
    }
}

gistfile3.txt

open class CoroutinesDispatcherProvider {
    open val main: CoroutineContext by lazy { Dispatchers.Main }
    open val io: CoroutineContext by lazy { Dispatchers.IO }
}