The way the descriptor mechanisms resolves the dot operator is an expensive thing. So by making it be written as length, uh, parion X, close parion, then temperature can resolve this much faster. If the structure is not a built in structure, then the interpreter falls back to looking up and then there's the cost of the attribute lookup,. But it will look up the dunder lane method. It gives us creators of APIs a way to provide a consistent interface that's consistent with the built in types.