function getUuid($separator = '-')
{
$str = md5(uniqid(mt_rand(100, 1000000), true));
$uuid = substr($str, 0, 8).$separator;
$uuid .= substr($str, 8, 4).$separator;
$uuid .= substr($str, 12, 4).$separator;
$uuid .= substr($str, 16, 4).$separator;
$uuid .= substr($str, 20, 12);
return $uuid;
}