public static function uniq($number)
{
$out = '';
$codes = '23456789abcdefghjkmnpqrstuvwxyz';
while ($number > 30) {
$key = $number % 31;
$number = floor($number / 31) - 1;
$out = $codes{$key}.$out;
}
return $codes{$number}.$out;
}