title: Returning the second number of pairs by filtering the first number
body: <p>Lets say I have pairs (1,2),(3, 9), (5, 6), (7,3), (9, 10)</p>
  <p>I want to return a list of the second part of the pair when the first part is greater than 4.</p>
  <p>So in the given example, I would return (6, 3, 10).</p>
  <p>Well what I've done is filter out the terms but don't know how to get the second parts.</p>
  <p>lets say <code>a</code> is the pair of sequence</p>
  <pre><code>a.filter(x=&gt;x._1 &gt; 4) // this filters out the pairs.. now i dont know how to cascade to return the second part as in x._2
  </code></pre>
  <p>any help would be appreciated.</p>
  <p>thanks in advance</p>