Method nested

include/fmt/format.h:3845–3845

        FMT_CONSTEXPR auto parse(format_parse_context& ctx) -> const char* { return formatter_.parse(ctx); }

        auto nested(const T& value) const -> nested_view<T> { return nested_view<T> {&formatter_, &value}; }
};

// DEPRECATED! join_view will be moved to ranges.h.