inline fun <reified T: Any> ViewModelStoreOwner.getOrCreatePersisted(create: () -> T): T

class PersistentStorage : ViewModel() {
    private val persisted = mutableMapOf<Class<*>, Any>()
    fun <T: Any> getOrCreate(clazz: Class<T>, create: () -> T) =
            persisted.getOrPut(clazz) { create.invoke() } as T
}
inline fun <reified T : Any> ViewModelStoreOwner.getOrCreatePersisted(noinline create: () -> T): T =
        ViewModelProvider(this).get<PersistentStorage>().getOrCreate(T::class.java, create)

val myVM = getOrCreatePersisted { MyMV(params) }

interface PersistentLifecycle {
    fun addOnClearResourcesListener(listener: () -> Unit)
}
class PersistentLifecycleImpl : ViewModel(), PersistentLifecycle {
    private val listeners = mutableListOf<() -> Unit>()
    override fun addOnClearResourcesListener(listener: () -> Unit) {
        listeners.add(listener)
    }
    override fun onCleared() {
        super.onCleared()
        for (listener in listeners) {
            listener.invoke()
        }
        listeners.clear()
    }
}
fun ViewModelStoreOwner.persistentLifecycle(): PersistentLifecycle =
        ViewModelProvider(this).get<PersistentLifecycleImpl>()

class MyViewModel(persistentLifecycle: PersistentLifecycle) {
    init {
        persistentLifecycle.addOnClearResourcesListener {
            // clean resources
        }
    }
}

class MyViewModel(
        private val coroutineScope: CoroutineScope
) {
    fun onSomethingClick() {
        coroutineScope.launch { 
            // do something 
        }
    }
}

class CoroutineScopeViewModel : ViewModel()
fun ViewModelStoreOwner.persistentCoroutineScope() =
        ViewModelProvider(this).get<CoroutineScopeViewModel>().viewModelScope

class MyViewModel(
        stateHelper: SavedStateHelper
) {
    private var screenId: String by stateHelper.savedState("screenId", default = "")
}

interface SavedStateHelper {
    fun <T: Any, VM : Any> savedState(key: String, default: T): ReadWriteProperty<VM, T>
}

class SavedStateHelperImpl(
        private val stateHandle: SavedStateHandle
) : ViewModel(), SavedStateHelper {
    override fun <T: Any, VM : Any> savedState(key: String, default: T): ReadWriteProperty<VM, T> {
        return PersistentStateDelegate(stateHandle, key, default)
    }
}
fun Fragment.savedStateHelper(): SavedStateHelper =
        ViewModelProvider(this, SavedStateViewModelFactory(requireActivity().application, this))
                .get<SavedStateHelperImpl>()
private class PersistentStateDelegate<T: Any>(
        private val holder: SavedStateHandle,
        private val key: String,
        private val default: T
) : ReadWriteProperty<Any, T> {
    override fun getValue(thisRef: Any, property: KProperty<*>): T {
        return holder.get<T>(getKey(thisRef))
            ?: default.also { setValue(thisRef, property, it) }
    }
    override fun setValue(thisRef: Any, property: KProperty<*>, value: T) {
        holder.set(getKey(thisRef), value)
    }
    private fun getKey(thisRef: Any) = "${thisRef.javaClass.name}__$key"
}

val viewModel = getOrCreatePersisted {
    MyViewModel(savedStateHelper(), persistentCoroutineScope(), persistentLifecycle())
}