Of mobile. Say luckily i had a cue which is happening so for each of these. I basically said this is why. I think it just doesn't make sense annoyed bad or it's rolling it just it doesn't make sense now. It may have been a good idea twenty years ago back in the kind of the golden age of. Oh if you like which is kind of the nineties. But then you know even something like the one i had the most trouble with those lists cough substitutes ability because bobby discovers a genius and and it's pretty obvious right if you're gonna have some rain. You gotta substitute itchy. Kinda do similar thing except that mostly nowadays even even in other languages wanna see mostly as competition rather than harrison's underwriting very much a change in a aesthetic she like of so programming style that people generally you might places might together comparison. And so having as if you're gonna only have five things having as one of them how to do inheritance redundant. That's how how to do something. That is no longer useful. Well let me jump in. If i may because the substitution principle says that. If you're in just correct me. If i'm wrong if you're going to substitute let's say an object with another object. You should pretty much do the same thing right. so what. if you're using the repository pattern. Does that work. I mean the whole idea behind repositories. You have an interface at different implementations based on maybe you're talking to different back ends right maybe you're talking to so what they actually do is completely different but within the context of the app. They're doing the same thing. Maybe data persistency would say is that. Well this is. What you've hit on is a popular misunderstanding of at us. paik about sometimes she'll type systems sometime. Not necessarily sub-clauses all implementations of things and.