function $(id){
 	return document.getElementById(id);
 }
 
 var current_content = 1;
 function get_content(cont_num){
 	if($('content_' + cont_num))
 	{
 		$('content_' + current_content).style.display = 'none';
 		$('tab_' + current_content).className = 'item disabled';
 		var content = $('content_' + cont_num);
 		var tab = $('tab_' + cont_num)
 		content.style.display='';
 		tab.className = 'item current';
 		current_content = cont_num
 	}
 }