add

fun <ViewType : View> ViewGroup.add(view: ViewType, index: Int = -1): ViewType
fun <ViewType : View> ViewGroup.add(    view: ViewType,     layout: ViewGroup.LayoutParams,     index: Int = -1): ViewType
fun <ViewType : View> ViewGroup.add(@LayoutRes layoutId: Int, index: Int = -1): ViewType
fun <ViewType : View> ViewGroup.add(    @LayoutRes layoutId: Int,     layout: ViewGroup.LayoutParams,     index: Int = -1): ViewType