="va">so</span><span class="op">)</span></span></span>
<span class="r-out co"><span class="r-pr">#&gt;</span> {1, 2}</span>
<span class="r-in"><span><span class="fu"><a href="add.html">add</a></span><span class="op">(</span><span class="va">so</span>, <span class="fl">0</span><span class="op">)</span></span></span>
<span class="r-out co"><span class="r-pr">#&gt;</span> {0, 1, 2}</span>
<span class="r-in"><span><span class="co"># Math</span></span></span>
<span class="r-in"><span><span class="va">s</span> <s