public function generate()
    {
        $html = array();

        foreach ($this->properties as $property => $value) {
            $html[] = strtr(static::OPENGRAPH_TAG, array(
                '[property]' => static::OPENGRAPH_PREFIX . $property,
                '[value]' => $value
            ));
        }

        return implode(PHP_EOL, $html);
    }