24 Iterators library [iterators]

24.5 Iterator adaptors [predef.iterators]

24.5.4 Move iterators and sentinels [move.iterators]

24.5.4.5 Conversion [move.iter.op.conv]

constexpr const Iterator& base() const & noexcept;
Returns: current.
constexpr Iterator base() &&;
Returns: std​::​move(current).