title: Add Flow for Boolean That Gets Updated
body: <p>I have a listener:</p>
  
  <pre><code>class Owner { 
      private lateinit var flow: Flow&lt;Boolean&gt;
  
      init {
          flow = callbackFlow {
          val callback = object : Listener {
  
              override fun onExit() {
                  offer(false)
              }
  
              override fun onEnter() {
                  offer(true)
              }
          }
          MyService.register(callback)
          awaitClose {
              //service.unregister(callback)
          }
      }
  
      fun getFlow(): Flow&lt;Boolean&gt; = flow 
  
  }
  </code></pre>
  
  <p>So then I want that every time the callback gets called the flow gets updated and any other class observing the flow would naturally get notified. How to do this?</p>
  
  <p>If I want to also set the value to <code>true</code> or <code>false</code> without the callback can I do it?</p>