use constant KILOBYTE => 2 ** 10;
use Judy::1 qw( Set MemUsed );
my $vec;
# 5,000 bits. Set every 100th bit between 15 million and 20 million.
for ( 15_000_000 .. 20_000_000 ) {
    if ( ! ( $_ % 100 ) ) {
        Set( $judy, $_ );
    }
}
printf "%0.1fK\n", MemUsed( $judy ) / KILOBYTE;