php function to unset variables passed by reference
<p>currently i'm using this php function :</p>

<pre><code>function if_exist(&amp;$argument, $default = '')
{
    if (isset ($argument))
    {
        echo $argument;
    }
    else
    {
        echo $default;
    }
}
</code></pre>

<p>i want this function to unset the variables $argument(passed by reference) and $default just after echoing their value, how can i do this?
Thanks in advance.</p>
