d = -1;
                <span class="keyword">else</span>
                    clicked = in;
                <span class="keyword">end</span>
            <span class="keyword">end</span>
        <span class="keyword">end</span>
</pre><h2>addClickToStack<a name="11"></a></h2><p>Adds an (<i>x</i>, <i>y</i>) coordinate to the stack <b>unless</b> it does not already exist. Multiples of clicks are not permitted.</p><p><b>Paramters</b></p><p><tt>x</tt>: x coordinate</p><p><tt>y</tt>: y coordinate</p><pre class="co