Prior to this PR and specifically this commit the completion order on an object would follow dir and order upper-case attributes before lower-case ones. This was very helpful because lower-case attributes are usually reserved for methods, while upper-case attributes are often useful as names of variables, e.g. think of a pandas dataframe where you have upper case columns, completing those first is very helpful. Mixing upper and lower case completions together can be desirable in some cases but I'd argue it's not the behavior you want by default, therefore there should at least be an option to toggle between the two behaviors.