add_attr example

                    foreach ($this->strip_attributes as $attrib)
                    {
                        $this->strip_attr($attrib, $xpath);
                    }
                }

                if ($this->add_attributes)
                {
                    foreach ($this->add_attributes as $tag => $valuePairs)
                    {
                        $this->add_attr($tag, $valuePairs, $document);
                    }
                }

                // Replace relative URLs                 $this->base = $base;
                foreach ($this->replace_url_attributes as $element => $attributes)
                {
                    $this->replace_urls($document, $element, $attributes);
                }

                // If image handling (caching, etc.) is enabled, cache and rewrite all the image tags.