event.  If you do
    not wish to write a new type-checker, feel free to skip this section
    of the tutorial.</p>
  </div>

  <div id="outline">
    <div class="well">
      <h5>Outline</h5>

      <ol>
        <li><a href="#setup">An Encryption Checker</a>
        </li>

        <li><a href="#annotation">Write type annotation
        definitions</a></li>

        <li><a href="#run1">Run the Encryption Checker &mdash; 2 errors</a></li>

        <li><a href="#error1">Suppress the first error</a></li>

    