constexpr transform_view(V base, F fun);
constexpr iterator<false> begin();
constexpr iterator<true> begin() const
requires range<const V> &&
regular_invocable<const F&, range_reference_t<const V>>;
constexpr sentinel<false> end();
constexpr iterator<false> end() requires common_range<V>;
constexpr sentinel<true> end() const
requires range<const V> &&
regular_invocable<const F&, range_reference_t<const V>>;
constexpr iterator<true> end() const
requires common_range<const V> &&
regular_invocable<const F&, range_reference_t<const V>>;