title: Cleaner tuple groupBy
body: <p>I have a sequence of key-value pairs (String, Int), and I want to group them by key into a sequence of values (i.e. <code>Seq[(String, Int)]) =&gt; Map[String, Iterable[Int]])</code>).</p>
  
  <p>Obviously, <code>toMap</code> isn't useful here, and <code>groupBy</code> maintains the values as tuples. The best I managed to come up with is:</p>
  
  <pre class="lang-scala prettyprint-override"><code>val seq: Seq[( String, Int )]
  // ...
  seq.groupBy( _._1 ).mapValues( _.map( _._2 ) )
  </code></pre>
  
  <p>Is there a cleaner way of doing this?</p>