concept ranges::random_access_iterator_ =
requires( I i, iter_difference_t<I> n ) { i + n, n + i, i - n, i += n, i -= n, concepts::requires_<same_as<
decltype(i + n), I>>, concepts::requires_<same_as<
decltype(n + i), I>>, concepts::requires_<same_as<
decltype(i - n), I>>, concepts::requires_<same_as<
decltype(i += n), I&>>, concepts::requires_<same_as<
decltype(i -= n), I&>>, concepts::requires_<same_as<
decltype(i[n]), iter_reference_t<I>>> ; }