title: Dummy nodes in linked lists
body: <p>Q: When are they used? (Homework question)</p>
  
  <ol>
  <li><p>1st and last node in the list</p></li>
  <li><p>Sometimes used as 1st and last nodes in the list</p></li>
  <li><p>Never used as 1st and last nodes in the list</p></li>
  </ol>
  
  <p>Wikipedia says,</p>
  
  <blockquote>
    <p>A sentinel node is a specifically designated node used with linked
    lists and trees as a traversal path terminator. A sentinel node does
    not hold or reference any data managed by the data structure.</p>
  </blockquote>
  
  <p>I'm thinking B but I don't really know.</p>