title: Kotlin - The feature "unit conversion" is disabled
body: <p>I am still a relative newbie at Kotlin and, after a fair bit of digging, cant fix what looks to be a simple problem.  For the code below the compiler returns: The feature &quot;unit conversion&quot; is disabled for
  &quot;function = positiveButtonClick&quot;
  and
  function = negativeButtonClick&quot;</p>
  <p>Why? What do I need to do?</p>
  <p>Thanks</p>
  <pre><code>    called with MessageBox(context, &quot;Hello Test&quot;, &quot;My Message&quot;);
  
  
      fun MessageBox(contxt: Context?, title: String, message: String): Boolean {
  
          val builder = AlertDialog.Builder(contxt)
  
          with(builder) {
              setTitle(title)
              setMessage(message)
              setPositiveButton(&quot;YES&quot;, DialogInterface.OnClickListener(function = positiveButtonClick))
              setNegativeButton(&quot;NO&quot;,  DialogInterface.OnClickListener(function = negativeButtonClick))
              show()
          }
  
          return false
      }
  
  
      val positiveButtonClick = { dialog: DialogInterface, which: Int -&gt; Unit
          Log.i(&quot;Dialog&quot;, &quot;Yes&quot;)
      }
  
      val negativeButtonClick = { dialog: DialogInterface, which: Int -&gt; Unit
          Log.i(&quot;Dialog&quot;, &quot;No&quot;)
      }
  </code></pre>