int64_t intsetRandom(intset *is) {
    uint32_t len = intrev32ifbe(is->length);
    assert(len); /* avoid division by zero on corrupt intset payload. */
    return _intsetGet(is,rand()%len);
}
int64_t intsetRandom(intset *is) {
    uint32_t len = intrev32ifbe(is->length);
    assert(len);  
    return _intsetGet(is,rand()%len);
}