public function getHtml($attribute = null)
        {
            if(null !== $attribute) {
                $attribute = strval($attribute);
                if(\Thin\Arrays::exists($attribute, $this->attributes)) {
                    return $attribute . '="' . implode(' ', $this->attributes[$attribute]) . '"';
                }
            } else {
                $return = array();
                foreach(array_keys($this->attributes) as $attrib) {
                    $return[] = $this->getHtml($attrib);
                }
                return implode(' ', $return);
            }

            return '';
        }