title: What's the postDelayed() uses in kotlin
body: <p>As I know postDelayed() have two argument runnable and duration delay.
  What actually does below code in kotlin:</p>
  
  <pre><code>Handler().postDelayed({
              sendMessage(MSG, params.id)
              taskFinished(params, false)
          }, duration)
  </code></pre>
  
  <p>Here 1st is two function calling and 2nd is duration delay. Where is runnable? Does this something like lambda for kotlin? Any anyone please explain this?</p>