A state object implemented with Kotlin's sealed classes

TabbedListState.kt

sealed class TabbedListState
class InProgressState : TabbedListState()
class FinishedState : TabbedListState()
data class ErrorState(val errorMessage: String,
                      val errorColor: Int) : TabbedListState()
data class ListState(val listElements: List<Element>,
                     val totalItems: Int,
                     val currentTabId: Int,
                     val tabs: List<TabElement>) : TabbedListState()
data class OfflineState(val listElements: List<Element>) : TabbedListState()

class Element
class TabElement