title: Query on Lambda syntax
body: <p>I am new to Lambda. I have the following queries on the code snippet given below.</p>
  <ol>
  <li><p>Who provides the values, reply &amp; failure?</p>
  </li>
  <li><p>I see 2 parameters reply &amp; failure here. Why not 1 or 3? Where do we define set of parameters?</p>
  </li>
  <li><p>Please refer me to any relevant tutorial for further understanding.</p>
  <pre><code> //Akka code snippet
   CompletionStage&lt;HashResult&gt; results = AskPattern.ask(....);
  
   results.whenComplete( (reply, failure) -&gt;  {
       if (reply == null) {
           System.out.println(&quot;Failure&quot;);
       }
       else {
           System.out.println(&quot;Success&quot;);
       }
   });
  </code></pre>
  </li>
  </ol>