public function printUsage($output, $prog)
    {
        $usageFile  = dirname(__DIR__) .
                        DIRECTORY_SEPARATOR . 'data' .
                        DIRECTORY_SEPARATOR . 'usage.txt';
        $usage      = @file_get_contents($usageFile);
        $usage      = str_replace(array("\r\n", "\r"), "\n", $usage);
        $usage      = trim($usage);
        $output->write($usage, $prog, 'http://xmlrpc.example.com/');
    }