access to successor
| 11507 | |
| 11508 | /// access to successor |
| 11509 | reference operator[](difference_type n) const |
| 11510 | { |
| 11511 | return *(this->operator+(n)); |
| 11512 | } |
| 11513 | |
| 11514 | /// return the key of an object iterator |
| 11515 | auto key() const -> decltype(std::declval<Base>().key()) |