static intset *createSet(int bits, int size) {
    uint64_t mask = (1<<bits)-1;
    uint64_t value;
    intset *is = intsetNew();

    for (int i = 0; i < size; i++) {
        if (bits > 32) {
            value = (rand()*rand()) & mask;
        } else {
            value = rand() & mask;
        }
        is = intsetAdd(is,value,NULL);
    }
    return is;
}