modify with inline and crossline

Event.kt

open class Event<out T>(private val content: T? = null) {
    @Suppress("MemberVisibilityCanBePrivate")
    var hasBeenHandled = false
        private set
    //  Returns the content and prevents its use again.
    fun getContentIfNotHandled(): T? = if (hasBeenHandled) null  else content.also { hasBeenHandled = true }
    //  Returns the content, even if it's already been handled.
  fun peekContent(): T? = content
}

inline fun <T> LiveData<Event<T>>.observeEvent(owner: LifecycleOwner, crossinline onEventUnhandledContent: (T) -> Unit) {
    observe(owner) { it?.getContentIfNotHandled()?.let(onEventUnhandledContent) }
}