33 struct cpp20_iterator {  struct
42     cpp20_iterator() = default;  argument
43     explicit cpp20_iterator(T* ptr) : my_ptr(ptr) {}  in cpp20_iterator()  function
47     cpp20_iterator& operator++() {  in operator ++()  argument
52     cpp20_iterator operator++(int) {  in operator ++()  argument
58     cpp20_iterator& operator--()  in operator --()  argument
65     cpp20_iterator operator--(int)  in operator --()  argument
73     cpp20_iterator& operator+=(difference_type n)  in operator +=()  argument
80     cpp20_iterator& operator-=(difference_type n)  in operator -=()  argument
93     friend bool operator==(const cpp20_iterator&, const cpp20_iterator&) = default;  argument
121 }; // class cpp20_iterator  argument