What does this mean?
<pre><code>function fkey(a) {
    a || (a = {});
    if (!a.fkey) a.fkey = $("input[name='fkey']").attr("value");
    return a
}
</code></pre>

<p>I guess <code>a</code> is actually a function, but how to understand <code>(!a.fkey)</code> ?</p>
