 derived from <code>Walker</code> called <code>Check</code>
that implements the checks the user wants.
The other command-line arguments must be the names of JavaScript source files to be checked:</p>
<div class="code-sample lang-sh" title="sniff.sh">
<div class="highlight"><pre><span></span><code>node<span class="w"> </span>sniff.js<span class="w"> </span>my-check.js<span class="w"> </span>source-1.js<span class="w"> </span>source-2.js
</code></pre></div>
</div>
<h3 class="exercise">Finding assertions</h3>
