I was just looking at runtime type checking. Apparently the reason nobody does it is because of the roughly 30,000% slowdown compared to not doing it. I e said

I was just looking at runtime type checking. Apparently the reason nobody does it is because of the roughly 30,000% slowdown compared to not doing it. I e said it before and I’ll say it again: runtime type checking saves you from the case where you pass None instead of an actual object but not much else. How wrong would your program have to be to pass an instance of Animal instead of an instance of BankAccount? And how quickly would it error out with “giraffe does not have an attribute routing_number”?