17         $string = trim($string);
 
   18         if ($string === 
'0') 
return $string;
 
   19         if ($string === 
'')  
return false;
 
   20         $length = strlen($string);
 
   21         if (substr($string, $length - 2) == 
'px') {
 
   22             $string = substr($string, 0, $length - 2);
 
   24         if (!is_numeric($string)) 
return false;
 
   27         if ($int < 0) 
return '0';
 
   33         if ($this->max !== null && $int > $this->max) 
return (
string) 
$this->max;
 
   39     public function make($string) {
 
   40         if ($string === 
'') 
$max = null;
 
   41         else $max = (int) $string;
 
   42         $class = get_class($this);
 
   43         return new $class(
$max);