function showcode(){
   var sel = document.getElementById('language_selection');
   var selected = sel.value;
   var pall = xGetElementsByTagName('*');
   for (i=0; i<pall.length; i++){
	var clss = pall[i].className;
	if (clss.substr(0,5)=='code-'){
	   if (clss==selected)
	       pall[i].style.display = 'block';
           else
	       pall[i].style.display = 'none';
        }
   }

}