">
<li>news</li>
<li>local</li>
<li>metro</li>
<li>crime_is_up</li>
</ol>
<p>The optional second parameter defaults to NULL and allows you to set the return value
of this method when the requested URI segment is missing.
For example, this would tell the method to return the number zero in the event of failure:</p>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="nv">$product_id</span> <span class="o">=</span> <span class="nv">$this</span><span class="o">-&gt;</span><span class