constexpr explicit split_view(V base, Pattern pattern);
template<forward_range R>
requires constructible_from<V, views::all_t<R>> &&
constructible_from<Pattern, single_view<range_value_t<R>>>
constexpr explicit split_view(R&& r, range_value_t<R> e);
constexpr iterator begin();
constexpr subrange<iterator_t<V>> find-next(iterator_t<V> it);