Should CodeList contain a dict of codes?

[phackstock]

While working on #205 I noticed that we are (almost) never using the lookup property that using a dictionary Dict[str, Code] over a list of Code objects gives us.
If there are no applications for the lookup I would suggest changing it so that CodeList contains an actual list of codes and not a dictionary.
Not a real priority though just something I noticed and might confuse contributors.

[danielhuppmann]

It may not be relevant for the automated processing, but when actually working with the DataStructureDefinition, I do find it helpful to look at the attributes of a variable from a Jupyter notebook environment like

DataStructureDefinition.variable["Final Energy"]

So I would keep a way to access a Code in this way.

[phackstock]

Fair point, that is a nice feature indeed. I'll close this one then.