perContext</cite> is specialized for
<cite>CommercialPaperContract</cite>. See how the custom context, addressed through <cite>this</cite>,
adds the specific variable <cite>PaperList</cite> to itself:</p>
<p><a href="#id6"><span class="problematic" id="id7">``</span></a><a href="#id8"><span class="problematic" id="id9">`</span></a>JavaScript
CommercialPaperContext extends Context {</p>
<blockquote>
<div><dl class="simple">
<dt>constructor () {</dt><dd><p>this.paperList = new PaperList(this);</p>
</dd>
</dl>