unless ( 
          GetOptions (
                        'url=s'                =>    \$url,
                        'agent=s'              =>    \$agent,
                        'extraparts|cache=i'   =>    \$cache_size,
                        'debug=i'              =>    \$debug,                        
                     );
) { die "$0 -url URL [-agent STRING -extraparts N -debug [0-2]]" }