Method extract

common/unordered_inline_set.h:137–145

            return !(*this == rhs);
        }
        T extract() {
            assert(_a && _i < _a->size());
            assert(_a->get_bit(_i));
            auto v = _a->get(_i);
            if (!v) return T();
            auto r = std::move(*v);
            _a->erase_bit(_i);
            return r;
        }
        iterator get_next() const {
            return ++iterator(*this);
        }