rem: memory_iterator& operator --() { data_ -= byte_io::byte_lenght<T>(); return *this; }
add: memory_iterator<T> operator -- ( memory_iterator<T>& ref, int ) { memory_iterator<T> copy = ref; --ref; return copy; }
context: 		memory_iterator& operator --() {			data_ -= byte_io::byte_lenght<T>();			return *this;		}