Result class refactoring

[alexey-kravtsov-tc]

Great project, thanks for sharing!

I have some minor improve suggestion - Result class is currently implemented in Java style and not getting benefits of the Kotlin compiler.

Having Result class implemented as

sealed class Result<out T> {
    class loading<T> : Result<T>()
    data class error<T>(val message: String) : Result<T>()
    data class success<T>(val data: T) : Result<T>()
}

you can avoid excess nullability checks(!!) and possible exceptions in places like

            if (responseStatus.status == SUCCESS) {
                saveCallResult(responseStatus.data!!)
            } else if (responseStatus.status == ERROR) {
                emit(Result.error<T>(responseStatus.message!!))
                emitSource(source)
            }

and have it in more Kotlin way

            if (responseStatus is Result.success) {
                saveCallResult(responseStatus.data)
            } else if (responseStatus is Result.error) {
                emit(Result.error<T>(responseStatus.message))
                emitSource(source)
            }

Hope you find it useful :)

[Eli-Fox]

That's great suggestion, @alexkrafts. I'll definitely take it as improvement.