Thanks everyone.
Def: You're right. I have tended to almost exclusively have types which only have abstract methods and functions in the base type though. For whatever reason I've never had implemented methods and functions in the base type, so I've never had them to consider. Of course, if it did otherwise, it would error trying to call an abstract function or method, but it still seems weird because I haven't done it like this before. You're right though, now that I think about it, it would be pretty useless if it worked any other way.
Def: You're right. I have tended to almost exclusively have types which only have abstract methods and functions in the base type though. For whatever reason I've never had implemented methods and functions in the base type, so I've never had them to consider. Of course, if it did otherwise, it would error trying to call an abstract function or method, but it still seems weird because I haven't done it like this before. You're right though, now that I think about it, it would be pretty useless if it worked any other way.