What does this script do?

[wxdqz]

Here's a really simple question - what does this script below do? Also, is there such a tool where you enter some script and it gets "translated" for you? ie, you can determine what a given piece of script will do? Thank you!

<script language="JavaScript" type="text/JavaScript">
<!--
function MM_findObj(n, d) { //v4.01
var p,i,x; if(!d) d=document;
if((p=n.indexOf("?"))>0&&parent.frames.length) {
d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++)
x=d.forms[n];
for(i=0;!x&&d.layers&&i<d.layers.length;i++)
x=MM_findObj(n,d.layers.document);
if(!x && d.getElementById) x=d.getElementById(n); return x;
}
//-->
</script>