9 Iterators library [iterators]

9.7 Iterator adaptors [iterators.predef]

9.7.3 Move iterators and sentinels [iterators.move]

9.7.3.2 move_iterator operations [move.iter.ops]

9.7.3.2.11 move_iterator::operator[] [move.iter.op.index]

constexpr reference operator[](difference_type n) const requires RandomAccessIterator<I>;

Effects: Equivalent to: return iter_move(current + n);