function getQueryVariable(variable) {
  var query = window.location.search.substring(1);
  var vars = query.split("&");
  for (var i=0;i<vars.length;i++) {
    var pair = vars[i].split("=");
    if (pair[0] == variable) {
      return pair[1];
    }
  }
  return null;
}
function changelang()
{
	lang = getQueryVariable('lang');
	if (lang==null || lang=='en')
	{
		window.location.href="?lang=fr";
	}else
	{
		window.location.href="?lang=en";
	}
		
}