sub decrement {
    my $string = shift;
    return '' unless length($string);
    my @parts = split//,$string;

    my $last = pop @parts;
    if( ord($last) == 32 ) {
        my $ret = decrement(join '',@parts);
        $ret .= (scalar @parts) ? "\x7E" : '';
        return $ret;
    } else {
        my $ret = join '',@parts,chr(ord($last)-1);
        return $ret;
    }
}