function parse($value)
 {
     if ($value === 'inherit') {
         return CSS_PROPERTY_INHERIT;
     }
     $value = MarginValue::init($this->parse_in($value));
     return $value;
 }
 function parse($string)
 {
     $value = MarginValue::init($this->parse_in($string));
     return $value;
 }