title: Subtract Seq[A] from Seq[B]
body: <p>I have two classes <code>A</code> and <code>B</code>. Both of them have the same property: <code>id</code> and many other different properties.</p>
  
  <p>How can I subtract <code>Seq[A]</code> from <code>Seq[B]</code> by matching the <code>id</code>'s?</p>