Generic wrapper class for handling states when retriving data from API or local databases.

Resource.kt

sealed class Resource<T>(val data: T? = null, val message: String? = null){
    class Success<T>(data: T) : Resource<T>(data)
    class Loading<T>(data: T? = null) : Resource<T>(data)
    class Error<T>(data: T? = null, message: String) : Resource<T> (data, message)
}