Good example of completely igoring the „data“ part. What are the inputs and outputs? In some cases it would make better sense to differentiate the train vehicle

Good example of completely igoring the „data“ part. What are the inputs and outputs? In some cases it would make better sense to differentiate the train vehicle by a type enum, where as in other situations it might make sense to derive from a general „vehicle“. why, when and how are the important things to think about and this should be taught.