ss the object by reference avoid this expense. The client and the function then share access to the single instance.</li>
</ul>

<div class="language-c++ bad col-sm-6 highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="c1">// slow because of copying</span>

<span class="kt">void</span> <span class="nf">process</span><span class="p">(</span><span class="n">Set</span><span class="o">&lt;</span><span class="n">string</span><span class="o">&gt;</span> <span class="n">data</span><