public function setCharset($charset = null)
    {
        if (! is_null($charset)) {
            $this->charset = $charset;
        } elseif (defined('THEMOSIS_CHARSET')) {
            $this->charset = THEMOSIS_CHARSET;
        } elseif (function_exists('get_bloginfo')) {
            $this->charset = get_bloginfo('charset');
        }

        return $this;
    }