Fragment tree with inputs and outputs

Fragments.kt

class FragmentWithDialog(output: (Output) -> Unit) : Fragment() {

    sealed class Output {
        object DialogShown : Output()
    }
}

class FragmentWithInput(input: Observable<Input>) : Fragment() {

    sealed class Input {
        object HideKeyboard : Input()
    }
}

class FragmentWithDialogAndInput : Fragment() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        // Add fragments to childFragmentManager and wire them
    }
}