Method test

highs/util/HighsHashTree.h:80–80

    void flip(uint8_t pos) { occupation ^= uint64_t{1} << (pos); }

    bool test(uint8_t pos) const { return occupation & (uint64_t{1} << pos); }

    int num_set_until(uint8_t pos) const {
      return HighsHashHelpers::popcnt(occupation >> pos);