b></p><p><tt>s</tt>: the new stack</p><pre class="codeinput">        <span class="keyword">function</span> setStack(obj, s)
            obj.stack = s;
        <span class="keyword">end</span>
</pre><h2>indexOf<a name="10"></a></h2><p>Return the position in the stack of coordinates (<i>x</i>, <i>y</i>), or -1 if they do not exist. Also returns -1 if the stack is empty.</p><p><b>Parameters</b></p><p><tt>x</tt>: x coordinate</p><p><tt>y</tt>: y coordinate</p><p><b>Returns</b></p><p><tt>clicked</tt>: position o