Effective C++ 19. type conversions

obejects of type T1 to be implicitly converted into objects of type T2
I.

class T1 {
public:
    operator T2(const T1& rhs) {
    ...
    }
    ...
};

II.

class T2{
public:
    T2 (const T1& rhs) {
    ...
    }
    ...
};