Class iterator

cpp/src/arrow/util/range.h:247–258

    constexpr sentinel end() const { return {}; }

    struct iterator {
      Int value{0};

      constexpr Int operator*() { return value; }

      constexpr iterator& operator++() {
        ++value;
        return *this;
      }

      constexpr std::true_type operator!=(sentinel) const { return {}; }
    };
    constexpr iterator begin() const { return {}; }
  } out;