 class="identifier">at</span><span class="special">(</span><span class="identifier">s</span><span class="special">)</span></code>
                    </p>
                  </td>
<td>
                    <p>
                      Return a reference to the object associated with symbol, <code class="computeroutput"><span class="identifier">s</span></code>. If <code class="computeroutput"><span class="identifier">sym</span></code>
                      does not already contain such an object, <code class="com