Method transform

include/ada/expected.h:1438–1440

    !defined(TL_EXPECTED_GCC54) && !defined(TL_EXPECTED_GCC55)
  template <class F>
  TL_EXPECTED_11_CONSTEXPR auto transform(F &&f) & {
    return expected_map_impl(*this, std::forward<F>(f));
  }
  template <class F>
  TL_EXPECTED_11_CONSTEXPR auto transform(F &&f) && {
    return expected_map_impl(std::move(*this), std::forward<F>(f));