public static function get_request_document() {
        $uri = $_SERVER['REQUEST_URI'];     // /tsugi/lti/some/cool/stuff
        $pieces = explode('/',$uri);
        if ( count($pieces) > 1 ) {
            $local_path = $pieces[count($pieces)-1];
            $pos = strpos($local_path,'?');
            if ( $pos > 0 ) $local_path = substr($local_path,0,$pos);
            return $local_path;
        }
        return false;
    }