function nocache_headers() { 
    // why are these @-silenced when other header calls aren't? 
    @header( 'Expires: Wed, 11 Jan 1984 05:00:00 GMT' ); 
    @header( 'Last-Modified: ' . gmdate( 'D, d M Y H:i:s' ) . ' GMT' ); 
    @header( 'Cache-Control: no-cache, must-revalidate, max-age=0' ); 
    @header( 'Pragma: no-cache' ); 
}