How to detect a JavaScript function with a certain signature has been registered?
<p>Say you have two functions with the following signatures:</p>

<ol>
<li><strong><code>addClass( class )</code></strong></li>
<li><strong><code>addClass( class, duration )</code></strong></li>
</ol>

<p>These live in a third party library <sub><sup>(no prizes for guessing which!!)</sup></sub>.</p>

<p>If you call <code>addClass()</code> with two parameters but only have signature 1 registered, there will be no error and signature 1 will be called. The second parameter is ignored.</p>

<p>So is there a way to detect that signature 2 <strong>with two parameters</strong> has been registered?</p>
