title: Enqueue to a Scala Queue another Scala Queue
body: <p>I want to enqueue to a Scala Queue another Scala Queue. Something like:</p>
  
  <pre><code>val q1 = Queue(1,2,3,4)
  val q2 = Queue(5,6,7,8)
  </code></pre>
  
  <p>I want to get a result like:</p>
  
  <pre><code>val q3 = Queue(1,2,3,4,5,6,7,8)
  </code></pre>
  
  <p>I already try this:</p>
  
  <pre><code>val q3 = (0 until q2.length).map(ind =&gt; q1.enqueue(q2(ind)))
  </code></pre>
  
  <p>But it return an  IndexedSeq[Unit] like below:</p>
  
  <pre><code>Vector((), (), (), ())
  </code></pre>
  
  <p>Do you have any idea?</p>