Three Uses of Inheritance?

I seem to recall coming across a post or comment on HN or somewhere else (really sorry, I am not able remember correctly) about how inheritance can only ever be used in three scenarios.

I think it referenced an article or post from some professor.

One such was Inheritance for re-use. Other two I do not remember.

I have been searching on and off for quite some time but have not been able to locate it.

Can anyone help?