An attribute will only work if you are given a list of employees or other iterable structure. My real example is that in my day job different business units of

An attribute will only work if you are given a list of employees or other iterable structure. My real example is that in my day job different business units of our customers are represented by a hierarchy, and you frequently traverse that hierarchy looking for some feature that's derived from the ancestor. But really this is any algorithm that looks up a tree.