Writing explicit `virtual`, `override`, or `final` is self-documenting and enables the compiler to catch mismatch of types and/or names between base and derived classes. However, writing more than one of these three is both redundant and a potential source of errors.
Use `virtual` only when declaring a new virtual function. Use `override` only when declaring an overrider. Use `final` only when declaring an final overrider.
Use `virtual` only when declaring a new virtual function. Use `override` only when declaring an overrider. Use `final` only when declaring an final overrider. If a base class destructor is declared `virtual`, derived class destructors should neither be declared `virtual` nor `override`.