What should a decorator do if an attribute already exists?

[Ethan Furman]

On 05/10/2016 08:45 AM, Steven D'Aprano wrote:

> I have a decorator that adds an attribute to the decorated function:

> My question is, what should I do if the decorated function already has an
> instrument attribute?

If the decorator is adding an attribute for the decorated thing to use, 
and that thing may already have the correct attribute, do nothing; 
otherwise, raise an exception.

--
~Ethan~